/**
  * returns the currently active routerplugin. Only one plugin may be active
  *
  * @return
  */
 public RouterPlugin getActivePlugin() {
   // convert only once
   String id = storage.getActivePluginID();
   if (id == null) {
     id = this.convertFromOldSystem();
     this.storage.setActivePluginID(id);
   }
   RouterPlugin active = ReconnectPluginController.getInstance().getPluginByID(id);
   if (active == null) {
     active = DummyRouterPlugin.getInstance();
     this.storage.setActivePluginID(active.getID());
   }
   return active;
 }