Support multicast for AXIS camera

[BrainLai]

Dear Sir:

Since AXIS camera requires the RTSP client to explicit request multicast SETUP, live555 has added an optional argument 'forceMulticastOnUnspecified' in RTSPClient::setupMediaSubsession() to force multicast.

Would you please integrate this setting into RTP/RTSP demux preference inferface?
Also, it should be convenient if RTP over TCP and RTP over HTTP are shown as more options in the page of Open Network.

BR.