fixes #2345 create piwigo standard pages

create new theme standard pages with tpl, css, js and images
update backend to handle pages
add config use_standard_pages
on update set config to false, on install set config to true
add standard pages to no be ingored in git

include/functions_user.inc.php

@@ -1048,6 +1048,29 @@ function log_user($user_id, $remember_me)
 {
   global $conf, $user;
 
+  //New default login and register pages, if users changes languages and succesfully logs in
+  //we want to update the userpref language stored in a cookie
+
+  //TODO check value of cookie
+
+  if (isset($_COOKIE['lang']) and $user['language'] != $_COOKIE['lang'])
+  {
+    if (!array_key_exists($_COOKIE['lang'], get_languages()))
+    {
+      fatal_error('[Hacking attempt] the input parameter "'.$_COOKIE['lang'].'" is not valid');
+    }
+
+    single_update(
+      USER_INFOS_TABLE,
+      array('language' => $_COOKIE['lang']),
+      array('user_id' => $user_id)
+    );
+
+    // We unset the lang cookie, if user has changed their language using interface we don't want to keep setting it back 
+    // to what was chosen using standard pages lang switch
+    setcookie("lang", "", time() - 3600);
+  }
+
   if ($remember_me and $conf['authorize_remembering'])
   {
     $now = time();

include/template.class.php

@@ -181,10 +181,21 @@ class Template
    */
   function set_theme($root, $theme, $path, $load_css=true, $load_local_head=true, $colorscheme='dark')
   {
-    $this->set_template_dir($root.'/'.$theme.'/'.$path);
-
     $themeconf = $this->load_themeconf($root.'/'.$theme);
 
+    // We loop over the theme and the parent theme, so if we exclude default, 
+    // standard pages can't get the header to load the html header
+    if (
+      'default' != $theme 
+      and in_array(script_basename(), array('identification', 'register', 'password')) 
+      and (($themeconf['use_standard_pages'] ?? false) or conf_get_param('use_standard_pages', false))
+    )
+    {
+      $theme = 'standard_pages';
+    }
+
+    $this->set_template_dir($root.'/'.$theme.'/'.$path);
+
     if (isset($themeconf['parent']) and $themeconf['parent'] != $theme)
     {
       $this->set_theme(