Stream: also connect to the right source, try to convert the name to
index when lookup fails, just like what pulseaudio does.
Implement more proplist functions, add some more info to the stream.
stream: handle NULL format
Improve introspection of the sink_input and source_output name, this
should be the media.name when possible.
context: fix memory free
subscribe: implement dummy methods
introspect: implement more
stream: keep track of dequeued buffers ourselves because we need to
be able to cancel and keep track of writable size.
