Accept only audio media in incoming audio/video calls
An incoming audio/video call must be presented to the user with the option to answer with audio media only.
New APIs were added to allow a client to selectively accept the media it wishes to use:
The media_negotiation unit test (test/unitTest/media_negotiation/media_negotiation.cpp) gives a good idea how the client and daemon should interact.\
relates to #389 (closed)