public function delete()
 {
     $view = $this->getView();
     $req = $this->getPageRequest();
     $mid = $req->getParameter(0);
     $m = new NavigationModel($mid);
     if (!$req->isPost()) {
         return View::ERROR_BADREQUEST;
     }
     if (!$m->exists()) {
         return View::ERROR_NOTFOUND;
     }
     $m->delete();
     \core\redirect('/navigation');
 }