diff --git a/functions.php b/functions.php
index cb13421..5b16324 100644
--- a/functions.php
+++ b/functions.php
@@ -1,1131 +1,1136 @@
 <?php
 # Copyright (C) 2015, 2016, 2017, 2018, 2019 Valerio Bozzolan
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
 # the Free Software Foundation, either version 3 of the License, or
 # (at your option) any later version.
 #
 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
 # along with this program. If not, see <http://www.gnu.org/licenses/>.
 
 /**
  * Check if the user do not want to be tracked
  *
  * See the HTTP 'DNT' header.
  *
  * @return boolean
  */
 function do_not_track() {
 	return isset( $_SERVER['HTTP_DNT'] )
 	           && $_SERVER['HTTP_DNT'] === '1';
 }
 
 
 /*
  * Configuration helpers
  *
  * Shortcuts useful when you declare a configuration file.
  */
 
 /**
  * Define a constant if it does not exist
  *
  * @param string $name  Constant name
  * @param string $value Constant value
  */
 function define_default( $name, $value ) {
 	defined( $name ) or
 	define(  $name, $value );
 }
 
 
 /*
  * Template helpers
  *
  * Shortcuts useful when you build a page
  */
 
 /**
  * Return a ' selected="selected"' HTML attribute under some circumstances
  *
  * @param mixed $helper  If this is the only arg, return
  * @param mixed $current If this matches $helper, return
  * @param bool  $force   If this is true, return
  */
 function selected( $helper = PHP_INT_MAX, $current = PHP_INT_MAX, $force = false ) {
 	return html_attribute_when_matching( 'selected', 'selected', $helper, $current, $force);
 }
 
 /**
  * Return a ' checked="checked"' HTML attribute under some circumstances
  *
  * This is useful for the <input type="checkbox" /> HTML tag.
  *
  * @param mixed $helper  If this is the only arg, return
  * @param mixed $current If this matches $helper, return
  * @param bool  $force   If this is true, return
  */
 function checked( $helper = PHP_INT_MAX, $current = PHP_INT_MAX, $force = false ) {
 	return html_attribute_when_matching( 'checked', 'checked', $helper, $current, $force);
 }
 
 /**
  * Return a ' disabled="disabled"' HTML attribute under some circumstances
  *
  * @param mixed $helper  If this is the only arg, return
  * @param mixed $current If this matches $helper, return
  * @param bool  $force   If this is true, return
  */
 function disabled( $helper = PHP_INT_MAX, $current = PHP_INT_MAX, $force = false ) {
 	return html_attribute_when_matching( 'disabled', 'disabled', $helper, $current, $force );
 }
 
 /**
  * Return an HTML attribute under some circumstances
  *
  * @param string $attribute HTML attribute name e.g. 'disabled'
  * @param string $value     HTML attribute value e.g.
  * @param mixed  $helper    If this is the only arg, return
  * @param mixed  $current   If this matches $helper, return
  * @param bool   $force     If this is true, return
  */
 function html_attribute_when_matching( $attribute, $value, $helper = PHP_INT_MAX, $current = PHP_INT_MAX, $force = false ) {
 	if( $helper === $current || $helper && PHP_INT_MAX === $current || $force ) {
 		return HTML::property( $attribute, $value );
 	}
 	return '';
 }
 
 /**
  * Get an HTML attribute ' value="$v"'
  *
  * The value will be sanitized.
  *
  * @param string $v
  * @return string
  */
 function value( $v ) {
 	return HTML::property( 'value', $v );
 }
 
 /**
  * Shortcut for htmlentities()
  *
  * Return an HTML-sanitized untrusted string to be safe from XSS.
  *
  * @param  string $s e.g. 'Hello<script>...'
  * @return string e.g. 'Hello&lt;script&gt;...'
  */
 function esc_html( $s ) {
 	return htmlentities( $s );
 }
 
 /**
  * Enfatize a sub-string
  *
  * This is helpful when highlighting search results
  *
  * @param  string $heystack e.g. 'The quick brown fox'
  * @param  string $needle   e.g. 'quick'
  * @param  string $pre      HTML markup put before the found $needle
  * @param  string $post     HTML markup put after fhe found $needle
  * @return string e.g. 'The <b>quick</b> brown fox'
  */
 function enfatize_substr( $heystack, $needle, $pre = '<b>', $post = '</b>' ) {
 	return OutputUtilities::enfatizeSubstr( $heystack, $needle, $pre, $post );
 }
 
 
 /*
  * Conversion shortcuts
  */
 
 
 /**
  * Force a variable to be an array
  *
  * @return mixed|array $a
  */
 function force_array( & $a ) {
 	if( ! is_array( $a ) ) {
 		$a = [ $a ];
 	}
 }
 
 
 /*
  * Database shourtcuts
  */
 
 /**
  * Sanitize an SQL value to be safe from SQL injections
  *
  * @param  string $s
  * @return string
  */
 function esc_sql( $s ) {
 	return DB::instance()->escapeString( $s );
 }
 
 /**
  * Sanitize an SQL value to be safe from SQL injections and escape also '%'
  *
  * @param  string $s
  * @return string
  */
 function esc_sql_like( $s ) {
 	$s = str_replace( '%', '\%', $s );
 	return esc_sql( $s );
 }
 
 /**
  * Execute whatever query
  *
  * @param string $query SQL query
  * @see DB#query()
  * @return object
  */
 function query( $query ) {
 	return DB::instance()->query( $query );
 }
 
 /**
  * Execute a query and return an array of objects
  *
  * Note: Use query_generator() if you do not need the entire array.
  *
  * @param  string $query      SQL query
  * @param  string $class_name Class name to encapsulate the result set
  * @param  array  $args       Arguments to be passed to the constructor of $class_name
  * @return array
  */
 function query_results( $query, $class_name = null, $args = [] ) {
 	return DB::instance()->getResults( $query, $class_name, $args );
 }
 
 /**
  * Execute a query and return a generator
  *
  * Note: Use query_results() if you need the entire array.
  *
  * @param  string $query      SQL query
  * @param  string $class_name Class name to encapsulate the result set
  * @param  array  $args       Arguments to be passed to the constructor of $class_name
  * @return array
  */
 function query_generator( $query, $class_name = null, $args = [] ) {
 	return DB::instance()->getGenerator( $query, $class_name, $args );
 }
 
 /**
  * Execute a query and return a single row, as an object
  *
  * @param  string       $query SQL  query
  * @param  string       $class_name Class name to encapsulate the result set
  * @return object|null              Arguments to be passed to the constructor of $class_name
  */
 function query_row( $query, $class_name = null, $args = [] ) {
 	return DB::instance()->getRow( $query, $class_name, $args );
 }
 
 /**
  * Execute a query and return a single column from a single row
  *
  * @param string $query SQL query
  * @param string $field Field to be returned
  * @see DB#getValue()
  */
 function query_value( $query, $field, $class_name = null ) {
 	return DB::instance()->getValue( $query, $field, $class_name );
 }
 
 /**
  * Executes multiple queries concatenated by a semicolon
  *
  * @param string $queries SQL queries
  */
 function multiquery( $queries ) {
 	return DB::instance()->multiQuery( $queries );
 }
 
 /**
  * Get a database table name, full with its prefix, eventually aliased
  *
  * Note that the prefix is declared in your configuration file as $prefix.
  *
  * @param  string  $table Table name e.g. 'test'
  * @param  boolean        If true, eventually strip the prefix with an alias
  * @return string         Table name e.g. 'site01_test'
  */
 function T( $table, $as = false ) {
 	return DB::instance()->getTable( $table, $as );
 }
 
 /**
  * Insert a row in a database table
  *
  * @param string  $table  Table name
  * @param DBCol[] $cols   Array of DBCol objects (with column, value and type)
  * @param array   $args   Associative arguments for the query
  *                          * 'replace-into' boolean Run a REPLACE INTO instead of just an INSERT INTO
  */
 function insert_row( $table, $cols, $args = [] ) {
 	return DB::instance()->insertRow( $table, $cols, $args );
 }
 
 /**
  * Get the last AUTOINCREMENT value created after an INSERT query
  *
  * @return int
  */
 function last_inserted_ID() {
 	if( ! DB::instanced() ) {
 		throw new SucklessException( 'cannot obtain last inserted ID without database connection' );
 	}
 	return DB::instance()->getLastInsertedID();
 }
 
 /**
  * Insert multiple rows in a database table
  *
  * @param string $table  Table name
  * @param array  $cols   Array of columns with their escape e.g. [ 'id' => 'd', 'name' => 's' ]
  * @param array  $values Array of rows e.g. [ [ 1, 'stallman' ], [ 2, 'torvalds' ]
  */
 function insert_values( $table, $cols, $values ) {
 	return DB::instance()->insert( $table, $cols, $values );
 }
 
 /**
  * Update rows in the specified database table
  *
  * @param string  $table Table name
  * @param DBCol[] $cols  Array of DBCol objects (with column, value and type)
  * @param string  $cond  SQL condition (after the WHERE part)
  * @see DB#update()
  */
 function query_update( $table, $cols, $cond, $after = '' ) {
 	DB::instance()->update( $table, $cols, $cond, $after );
 }
 
 /**
  * Shortcut for htmlspecialchars()
  *
  * Get a sanitized value for an HTML attribute value (in double quotes).
  *
  * @param string $s
  * @return string
  */
 function esc_attr( $s ) {
 	return htmlspecialchars( $s );
 }
 
 /**
  * Shortcut for echoing htmlspecialchars()
  *
  * Print a sanitized value for an HTML attribute value (in double quotes).
  *
  * @param string $s
  */
 function _esc_attr( $s ) {
 	echo htmlspecialchars( $s );
 }
 
 /**
  * Associate some MIME types to a category
  *
  * @param string $category  e.g. 'compressed'
  * @param string $mimetypes e.g. [ 'tgz' => 'application/x-tar', 'gzip' => 'application/x-bzip', ]
  */
 function register_mimetypes( $category, $mimetypes ) {
 	MimeTypes::instance()->registerMimetypes($category, $mimetypes);
 }
 
 /**
  * Get the MIME types of a category, or all the accepteds
  *
  * @param  string $category e.g. 'image'
  * @return string
  */
 function get_mimetypes( $category = null ) {
 	return MimeTypes::instance()->getMimetypes( $category );
 }
 
 /**
  * Register permissions to a role
  *
  * @param string       $role        User role
  * @param array|string $permissions Permissions
  */
 function register_permissions($role, $permissions) {
 	Permissions::instance()->registerPermissions($role, $permissions);
 }
 
 /**
  * Give some permissions to a role, inheriting from an old one
  *
  * @param string       $role_to     Role to give permissions
  * @param string       $role_from   Role from inheriting permissions
  * @param array|string $permissions Extra permissions to be add to $role_to
  */
 function inherit_permissions( $role_to, $role_from, $permissions = [] ) {
 	Permissions::instance()->inheritPermissions( $role_to, $role_from, $permissions );
 }
 
 /**
  * Register a JavaScript file to be enqueued later
  *
  * @param string $uid          Script name e.g. 'jquery'
  * @param string $url          Script URL e.g. '/javascript/jquery/jquery.min.js'
  * @param string $position     Choose between 'header' or 'footer'
  * @param array  $dependencies Array of script names used as dependencies
  */
 function register_js( $uid, $url, $position = null, $dependencies = [] ) {
 	RegisterJS::instance()->register( $uid, $url, $position, $dependencies );
 }
 
 /**
  * Register an inline JavaScript script and attach to a registered script
  *
  * @param string $uid      Dependent script name e.g. 'jquery'
  * @param string $data     Script body e.g. '$(document).find()...'
  * @param string $position Choose between 'after' or 'before' related to $uid execution
  */
 function register_js_inline( $uid, $data, $position = 'after' ) {
 	RegisterJS::instance()->registerInline($uid, $data, $position);
 }
 
 /**
  * Register an inline JavaScript variable and attach to a registered script
  *
  * @param string $uid      Dependent script name e.g. 'my-map'
  * @param string $variable Variable declaration e.g. 'var coordinates'
  * @param mixed  $value    Variable content (can be an array, an object, a callback, etc.)
  * @param string $position Choose between 'after' or 'before' related to $uid execution
  */
 function register_js_var( $uid, $variable, $value, $position = 'before' ) {
 	if( is_closure( $value ) ) {
 		$value = $value();
 	}
 	$data = json_encode( $value, DEBUG ? JSON_PRETTY_PRINT : 0 );
 	register_js_inline( $uid, "$variable = $data;", $position );
 }
 
 /**
  * Mark a registered script for usage
  *
  * Note that if there is a related stylesheet, it will be enqueued as well.
  *
  * @param string $uid      Dependent script name e.g. 'my-map'
  * @param string $position Choose between 'header' or 'footer'
  */
 function enqueue_js( $uid, $position = null ) {
 	return RegisterJS::instance()->enqueue( $uid, $position );
 }
 
 /**
  * Register a CSS stylesheet
  *
  * @param string $uid Stylesheet name e.g. 'materializecss'
  * @param string $url Stylesheet URL
  */
 function register_css( $uid, $url ) {
 	return RegisterCSS::instance()->register( $uid, $url );
 }
 
 /**
  * Mark a registered stylesheet for usage
  *
  * @param string $uid Stylesheet name e.g. 'materializecss'
  */
 function enqueue_css( $uid ) {
 	return RegisterCSS::instance()->enqueue( $uid );
 }
 
 /**
  * Register some menu entries
  *
  * @param MenuEntry[] $entries
  */
 function add_menu_entries( $entries ) {
 	Menu::instance()->add( $entries );
 }
 
 /**
  * Get a menu entry
  *
  * @param string $uid
  * @return MenuEntry
  */
 function menu_entry( $uid ) {
 	return Menu::instance()->getMenuEntry( $uid );
 }
 
 function get_children_menu_entries($uid) {
 	return Menu::instance()->getChildrenMenuEntries($uid);
 }
 
 /**
  * Register a module
  *
  * @param string $uid Module position
  */
 function register_module( $uid ) {
 	return RegisterModule::instance()->register($uid);
 }
 
 /**
  * Inject a closure into a module
  *
  * @param string $uid
  * @param closure $callback
  */
 function inject_in_module( $uid, $callback ) {
 	return RegisterModule::instance()->injectFunction($uid, $callback);
 }
 
 /**
  * Run the actions registered in the specified module
  *
  * @param string $uid
  */
 function load_module( $uid ) {
 	return RegisterModule::instance()->loadModule($uid);
 }
 
 /**
  * Get the database table prefix
  *
  * @return string
  */
 function get_table_prefix() {
 	return DB::instance()->getPrefix();
 }
 
 /**
  * Register an option to be used later
  *
  * The options are stored in the database.
  *
  * @param string $name
  */
 function register_option( $name ) {
 	return DB::instance()->registerOption( $name );
 }
 
 /**
  * Get the value of an option
  *
  * The options are stored in the database.
  *
  * @param string $name Option name
  * @param string $default Option default value
  * @return string Option value
  */
 function get_option( $name, $default = '' ) {
 	return Options::instance()->get( $name, $default );
 }
 
 /**
  * Set the value of an option
  *
  * The options are stored in the database.
  *
  * @param string  $name     Option name
  * @param string  $value    Option value
  * @param boolean $autoload Set to false if this option is not used on the majority of the requests
  */
 function set_option( $name, $value, $autoload = true ) {
 	return Options::instance()->set( $name, $value, $autoload );
 }
 
 /**
  * Remove an option
  *
  * The options are stored in the database.
  *
  * @param string $name Option name
  */
 function remove_option( $name ) {
 	return Options::instance()->remove( $name );
 }
 
 /**
  * Get the current logged user, or just a property
  *
  * @param  string $property Property name or NULL to retrieve the whole object
  * @return object           Value of $property, or entire user (Sessionuser) object if $property is NULL
  */
 function get_user( $property = null ) {
 	$user = Session::instance()->getUser();
 	if( $property === null ) {
 		return $user;
 	}
 	return $user ? $user->get( $property ) : null;
 }
 
 /**
  * Try to login using POST 'user_uid' and 'user_password' fields
  *
  * Note that this will not involve sessions.
  *
  * @param  int    $status Login status code
  * @param  string $uid    User uid
  * @param  string $pwd    Password
  * @return boolean        Login successful or not
  */
 function login(& $status = null, $uid = null, $pwd = null) {
 	return Session::instance()->login($status, $uid, $pwd);
 }
 
 /**
  * Destroy user cookies
  */
 function logout() {
 	return Session::instance()->destroy();
 }
 
 /**
  * To be used inside a form with POST method to contrast CSRF attacks
  *
  * @param string $action Your action name e.g. 'save-user'
  */
 function form_action( $action ) {
 	Session::instance()->formActionWithCSRF( $action );
 }
 
 /**
  * Check if a POST action is the specified one
  *
  * @param string $action Your action name e.g. 'save-user'
  * @return boolean
  */
 function is_action( $action ) {
 	return Session::instance()->validateActionAndCSRF( $action );
 }
 
 /**
  * Require a CSRF token to use the actual page
  */
 function require_csrf() {
 	Session::instance()->getCSRF();
 }
 
 /**
  * Register a language
  *
  * @param string $code    Language code e.g. 'en_US'
  * @param array  $aliases Language aliases e.g. [ 'en_GB' ]
  * @param string $iso     Language iso code e.g. 'en'
  * @param string $human   Human language name e.g. 'English'
  */
 function register_language( $code, $aliases = [], $encode = null, $iso = null, $human = null ) {
 	return RegisterLanguage::instance()->registerLanguage( $code, $aliases, $encode, $iso, $human );
 }
 
 /**
  * Register the default language
  *
  * @param string $lang Language code, language alias, etc. e.g. 'en'
  */
 function register_default_language( $lang ) {
 	return RegisterLanguage::instance()->setDefaultLanguage( $lang );
 }
 
 /**
  * Find a language
  *
  * @param string $lang Language code, language alias, etc. e.g. 'en'
  */
 function find_language( $lang ) {
 	return RegisterLanguage::instance()->getLanguage( $lang );
 }
 
 /**
  * Apply a language to the next translations
  *
  * @param  string $lang Language code, language alias, etc e.g. 'en'
  * @return object       Language object
  */
 function apply_language( $lang = null ) {
 	return RegisterLanguage::instance()->applyLanguage( $lang );
 }
 
 /**
  * Retrieve the latest language applied
  *
  * @return object
  */
 function latest_language() {
 	return RegisterLanguage::instance()->getLatestLanguageApplied();
 }
 
 /**
  * Get a list of all the registered languages
  *
  * @return array
  */
 function all_languages() {
 	return RegisterLanguage::instance()->getAll();
 }
 
 /**
  * Get the number of queries run
  *
  * @return int
  */
 function get_num_queries() {
 	if( DB::instanced() ) {
 		return DB::instance()->queries;
 	}
 	return 0;
 }
 
 /**
  * Check if the user is authenticated
  *
  * @return boolean
  */
 function is_logged() {
 	return Session::instance()->isLogged();
 }
 
 /**
  * Check if the user has a permission
  *
  * @param string $permission Permission code
  * @param object $user       An user object, different from the current one
  * @return bool
  */
 function has_permission( $permission, $user = null ) {
 	return Permissions::instance()->userHasPermission( $permission, $user );
 }
 
 /**
  * Add a directory to a base URL or a pathname
  *
  * If the base URL it is not defined, a slash ('/') is appended to the URL.
  * The base URL could end with a slash ('/') or not.
  *
- * @param  string $base Base URL with/without any slash at start
- * @param  string $dir  Directory without any slash
- * @return string       URL / Pathname
+ * @param  string $base Base URL or pathname with/without any slash at start
+ * @param  string $dir  Directory or partial pathname with or without initial slashes
+ * @param  string $glue Directory separator (as default it's the '/' for URLs)
+ * @return string       The junction between $base and $glue
 */
-function append_dir( $base, $dir = '/' ) {
-	$base = rtrim( $base, '/' );
-	$dir  = ltrim( $dir, '/' );
-	return $base . _ . $dir;
+function append_dir( $base, $dir = '', $glue = null ) {
+	if( !$glue ) {
+		// pick default URL separator '/'
+		$glue = _;
+	}
+	$base = rtrim( $base, $glue );
+	$dir  = ltrim( $dir,  $glue );
+	return $base . $glue . $dir;
 }
 
 /**
  * Normalize a partial URI to a complete one, or an absolute one
  *
  * Few examples:
  *   * If the URI is an anchor, keep it as-is
  *   * If the URI starts with a protocol, keep it as-is
  *   * If the URI starts with a slash, keep it as-is or, if $full_url, append protocol and domain
  *   * If the URI it's a word like 'page.html', prepend ROOT or, if $full_url, append also protocol and domain
  *
  * @param $page     string  Whatever, a full URL, a relative pathname e.g. 'page.html', an absolute one, etc.
  * @param $full_url boolean Set to true if you want an URI with it's protocol and domain, and not just the pathname
  */
 function site_page( $page, $full_url = false ) {
 	$first = @$page[ 0 ];
 
 	if( $first === '#' ) {
 		return $page; // an anchor e.g. '#contacts'
 	}
 
 	if( $first === '/' ) {
 		if( @$page[ 1 ] === '/' ) {
 			return $page; // URI with relative protocol e.g. '//example.org'
 		}
 
 		return append_dir( $full_url ? BASE_URL : '', $page );
 	} elseif( preg_match( '#^[a-z]+://#', $page ) === 1 ) {
 		return $page; // URI with full protocol e.g. 'ftp://example.org'
 	}
 
 	// URI not starting with a slash e.g. 'contact.html'
 	return append_dir( $full_url ? URL : ROOT, $page );
 }
 
 /**
  * Choose the appropriate string.
  * '%' will be replaced with the input number.
  *
  * @param int $n Input number.
  * @param string $text_multi Text displayed if n > 1
  * @param string $text_one Text displayed if n == 1
  * @param string $text_no Text displayed if n < 1
  */
 function multi_text( $n, $text_multi, $text_one, $text_no = '' ) {
 	if( $n > 1 ) {
 		return str_replace( '%', $n, $text_multi );
 	}
 	return $n == 1 ? $text_one : $text_no;
 }
 
 /**
  * Do an HTTP redirects and die
  *
  * @param string $url           URL (can be relative)
  * @param string $response_code HTTP response code (PHP's default it's 302)
  */
 function http_redirect( $url, $response_code = 0 ) {
 	$url = site_page( $url, true );
 	header( "Location: $url", true, $response_code );
 	exit;
 }
 
 /**
  * Get a search-engine friendly version of any string
  *
  * @param  string  $s          Input string
  * @param  int     $max_length Maximum string length (or zero for no limit)
  * @param  string  $glue       Word separator
  * @param  boolean $truncated  Flag to know if the string was truncated
  * @return string
  */
 function generate_slug( $s, $max_length = 0, $glue = '-', & $truncated = false ) {
 	return OutputUtilities::slug( $s, $max_length, $glue, $truncated );
 }
 
 /**
  * Build an HTTP GET URL from an associative array of arguments
  *
  * Note that NULL arguments will be automatically stripped out.
  *
  * @param  string $url  Input URL e.g. 'https://example.com/page.html'
  * @param  array  $data Associative array of parameters e.g. [ 'p' => '1' ]
  * @return string URL with GET data e.g. 'https://example.com/page.html?p=1'
  */
 function http_build_get_query( $url, $data ) {
 	$data = http_build_query( $data );
 	return $data ? "$url?$data" : $url;
 }
 
 /**
  * HTTP 503 header
  *
  * Spawn a 503 HTTP status code
  */
 function http_503() {
 	OutputUtilities::header503();
 }
 
 /**
  * Scare the user with an error message and die
  *
  * @param string $msg
  */
 function error_die( $msg ) {
 	OutputUtilities::WSOD( $msg );
 }
 
 /**
  * Log an error message and eventually print it when DEBUG
  *
  * @param string $msg
  * @return void
  */
 function error( $msg ) {
 	OutputUtilities::error( $msg );
 }
 
 /**
  * Translate a string
  *
  * You should understand the amazing GNU Gettext workflow.
  *
  * @param  string $msgid  String to be translated
  * @param  string $domain Translation domain
  * @return string         Translated string (or original one)
  */
 function __( $msgid, $domain = '' ) {
 	// is native GNU GETTEXT implementation?
 	static $native = null;
 	if( null === $native ) {
 		$native = RegisterLanguage::instance()->isNative();
 	}
 
 	// low-level GNU Gettext call
 	if( $native ) {
 		return _( $msgid );
 	}
 
 	// high-level GNU Gettext (simpler but slower)
 	return MoLoader::instance()->getTranslator( $domain )->gettext( $msgid );
 }
 
 /**
  * Shortcut for echoing a translated string
  *
  * @param  string $msgid  String to be translated
  * @param  string $domain Translation domain
  * @return string         Translated string (or original one)
  */
 function _e( $msgid, $domain = '' ) {
 	echo __( $msgid, $domain );
 }
 
 /**
  * Declare a JSON document
  *
  * @param string $charset Document charset, if different from the default one
  */
 function http_json_header( $charset = null ) {
 	if( !$charset ) {
 		$charset = CHARSET;
 	}
 	header( "Content-Type: application/json; charset=$charset" );
 }
 
 /**
  * Send a JSON (stripping out unuseful values) and die
  *
  * For performance related to data transfer, falsy elements are stripped out.
  *
  * @param $data mixed
  */
 function json( $data, $flags = 0 ) {
 	http_json_header();
 	$data = OutputUtilities::compressData( $data );
 	echo json_encode( $data, $flags );
 	exit;
 }
 
 /**
  * Send a JSON error and die
  *
  * Note that in the real world it does not exist a JSON error,
  * this method is just a way to standardize it a bit.
  *
  * @param int    $http_code HTTP response status code e.g. '403'
  * @param string $code      Human error code e.g. 'unauthorized'
  * @param string $msg       Human error message e.g. 'You are not authorized to....'
  * @param int    $flags     Flags passed to json_encode()
  */
 function json_error( $http_code, $code, $msg = null, $flags = 0 ) {
 	http_response_code( $http_code );
 	json( [ 'error' => [
 		'code'    => $code,
 		'message' => $msg,
 	] ], $flags );
 }
 
 /**
  * Get the MIME type of a file
  *
  * @param string $filepath Filesystem file path
  * @see MimeTypes::fileMimetype()
  */
 function get_mimetype( $filepath, $pure = false ) {
 	return MimeTypes::fileMimetype( $filepath, $pure = false );
 }
 
 /**
  * Check if a file belongs to a certain category
  *
  * @param string $filepath Filesystem file path
  * @param string $category File category e.g. 'image'
  * @see MimeTypes#isMimetypeInCategory()
  */
 function is_file_in_category( $filepath, $category ) {
 	$mime = get_mimetype( $filepath );
 	return MimeTypes::instance()->isMimetypeInCategory( $mime, $category );
 }
 
 /**
  * Extract the file extension from a filename (if it respects the file MIME type)
  *
  * @param  string $filename Filesystem file path
  * @param  string $category File category e.g. 'image'
  * @return mixed File extension or false if it was not found
  */
 function get_file_extension_from_expectations( $filename, $category ) {
 	return MimeTypes::instance()->getFileExtensionFromExpectations( $filename, $category );
 }
 
 /**
  * Check if a file is an image
  *
  * @param string $filepath
  * @return boolean
  */
 function is_image( $path ) {
 	return is_file_in_category( $path, 'image' );
 }
 
 /**
  * Check if a file is an audio
  *
  * @param string $path
  * @return boolean
  */
 function is_audio( $path ) {
 	return is_file_in_category( $path, 'audio' );
 }
 
 /**
  * Check if a file is a video
  *
  * @param string $path
  * @return boolean
  */
 function is_video( $path ) {
 	return is_file_in_category( $path, 'video' );
 }
 
 /**
  * Check if a file is a document
  *
  * @param string $path
  */
 function is_document( $path ) {
 	return is_file_in_category( $path, 'document' );
 }
 
 /**
  * Validate a closure
  *
  * @param mixed $t
  * @return boolean
  */
 function is_closure( $t ) {
 	return is_object( $t ) && $t instanceof Closure;
 }
 
 /**
  * Get the human filesize from bytes
  *
  * @param $filesize int bytes
  * @param $glue string
  * @return string
  */
 function human_filesize( $filesize, $glue = ' ' ) {
 	return OutputUtilities::humanFilesize( $filesize, $glue );
 }
 
 /*
  * Create a directory
  *
  * @param $path string
  * @param $chmod string
  */
 function create_path( $path, $chmod = null ) {
 	return FileUploader::createPath( $path, $chmod );
 }
 
 /**
  * @see FileUploader::searchFreeFilename()
  */
 function search_free_filename( $filepath, $filename, $ext, $args, $build_filename = null ) {
 	return FileUploader::searchFreeFilename( $filepath, $filename, $ext, $args, $build_filename );
 }
 
 /**
  * I use this to clean user input before DB#insert()
  *
  * This does not mean that it sanitizes the string.
  *
  * @param string $s Input string
  * @param int $max Max length
  * @return string
  */
 function luser_input( $s, $max ) {
 	return mb_strimwidth( trim( $s ), 0, $max, '' );
 }
 
 /**
  * Get the number of milliseconds of this request age
  *
  * @param int $precision number of decimal digits to round to
  * @return Execution time
  */
 function get_page_load( $decimals = 6 ) {
 	return round( microtime( true ) - $_SERVER[ 'REQUEST_TIME_FLOAT' ], $decimals );
 }
 
 // shortcuts to build SELECT * query
 define('DOT',  '.');
 define('STAR', '*');
 
 /*
  * Deprecated zone
  *
  * @TODO remove the shit below this line
  */
 
 /**
  * Truncate a string if it's over a specific length
  *
  * You can specify the end of the string if it's truncated.
  *
  * @param string $s          Input string
  * @param int    $max_length Max string length
  * @param string $blabla     Optional. If $s length is over $max_length, $blabla it's appended after $s
  * @deprecated Use mb_strimwidth
  */
 function str_truncate($s, $max_length, $blabla = '', $encoding = null ) {
 	error( "deprecated str_truncate() use mb_strimwidth() instead" );
 	if( ! $encoding ) {
 		$encoding = mb_internal_encoding();
 	}
 	return mb_strimwidth($s, 0, $max_length, $blabla, $encoding);
 }
 
 define('T', 'T');
 
 define('JOIN', 'JOIN');
 
 // Stupid shurtcut for string context
 $GLOBALS[T] = function( $t, $as = false ) {
 	return T($t, $as = false);
 };
 
 // Stupid shortcut for string context for listing tables
 $GLOBALS[JOIN] = function( $t ) {
 	return DB::instance()->getTables( func_get_args() );
 };
 
 function get_menu_entry( $uid ) {
 	error( "deprecated get_menu_entry() use menu_entry() instead" );
 	return menu_entry( $uid );
 }
 
 function _esc_html( $s ) {
 	error( 'deprecated _esc_html' );
 	echo htmlentities( $s );
 }
 
 function _checked( $helper = PHP_INT_MAX, $current = PHP_INT_MAX, $force = false ) {
 	error( 'deprecated _checked() use echo checked()' );
 	echo checked( $helper, $current, $force );
 }
 
 function _selected( $helper = PHP_INT_MAX, $current = PHP_INT_MAX, $force = false ) {
 	error( 'deprecated _selected() use echo selected()' );
 	echo selected( $helper, $current, $force );
 }
 
 function _disabled( $helper = PHP_INT_MAX, $current = PHP_INT_MAX, $force = false ) {
 	error( 'deprecated _disabled() use echo disabled()' );
 	echo disabled( $helper, $current, $force );
 }
 
 function _required( $helper = PHP_INT_MAX, $current = PHP_INT_MAX, $force = false ) {
 	error( 'deprecated _required() print it instead' );
 	echo html_attribute_when_matching( 'required', 'required', $helper, $current, $force );
 }
 
 function _value( $v ) {
 	error( 'deprecated _value() use echo value() insted' );
 	echo value( $v );
 }
diff --git a/tests/TestFilesystem.php b/tests/TestFilesystem.php
new file mode 100644
index 0000000..fefd083
--- /dev/null
+++ b/tests/TestFilesystem.php
@@ -0,0 +1,60 @@
+<?php
+// use the phpunit framework
+use PHPUnit\Framework\TestCase;
+
+/**
+ * Test Query class
+ */
+final class TestFilesystem extends TestCase {
+
+	/**
+	 * Test the append_dir() function
+	 */
+	public function testAppendDir1() {
+		$this->assertEquals(
+			append_dir( 'asd', 'dsa' ),
+			'asd/dsa'
+		);
+	}
+
+	/**
+	 * Test the append_dir() function
+	 */
+	public function testAppendDir2() {
+		$this->assertEquals(
+			append_dir( 'asd/', 'dsa' ),
+			'asd/dsa'
+		);
+	}
+
+	/**
+	 * Test the append_dir() function
+	 */
+	public function testAppendDir3() {
+		$this->assertEquals(
+			append_dir( 'asd', '/dsa' ),
+			'asd/dsa'
+		);
+	}
+
+	/**
+	 * Test the append_dir() function
+	 */
+	public function testAppendDir4() {
+		$this->assertEquals(
+			append_dir( 'asd/', '/dsa' ),
+			'asd/dsa'
+		);
+	}
+
+	/**
+	 * Test the append_dir() function with a custom glue
+	 */
+	public function testAppendDirCustomGlue() {
+		$this->assertEquals(
+			append_dir( 'asd\\', '\\dsa', '\\' ),
+			'asd\\dsa' // intended as "asd\dsa"
+		);
+	}
+
+}