/**
  * Log user in using the standard Chamilo way of logging in.
  * Useful when the normal login screen is removed from the user interface
  * - replaced by Shibboleth login - and user want to login using a standard
  * account
  */
 public function admin_login()
 {
     $title = get_lang('internal_login');
     if (Shibboleth::session()->is_logged_in()) {
         $message = get_lang('already_logged_in');
         Shibboleth::display()->message_page($message, $title);
     }
     $html = PageController::displayLoginForm();
     Shibboleth::display()->page($html, $title);
 }