* Fixed ControlPoint::stop() to set null the ControlPoint pointers in SSDPNotifySocketList and SSDPSearchResponseSocketList.
* Fixed ControlPoint::stop() to remove from listner of HTTPServerList.
* Fixed Device::stop() to remove from listners of HTTPServerList, SSDPSearchSocketList.
* Added SSDPSearchSocketList::removeSearchListener().
* Removed SSDPSearchResponseSocket member in ControlPoint because the instance is not used.