/**
  * clear hooks
  * @param string signalclass
  * @param string signalname
  */
 public static function clear($signalclass = '', $signalname = '')
 {
     if ($signalclass) {
         if ($signalname) {
             self::$registered[$signalclass][$signalname] = array();
         } else {
             self::$registered[$signalclass] = array();
         }
     } else {
         self::$registered = array();
     }
 }