don't assign by reference, declare filter variable, fixes #1338

Closes #1338

Merge request studip/studip!826

app/controllers/resources/room_request.php

@@ -21,6 +21,8 @@
  */
 class Resources_RoomRequestController extends AuthenticatedController
 {
+    protected $filter;
+
     public function before_filter(&$action, &$args)
     {
         parent::before_filter($action, $args);

app/controllers/studip_controller.php

@@ -234,7 +234,7 @@ abstract class StudipController extends Trails_Controller
 
                     $arg = $sorm;
                     if ($this->_autobind) {
-                        $this->{$info['var']} =& $arg;
+                        $this->{$info['var']} = $arg;
                     }
                     break;