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.
Brain Lai