Improve RTSP/RTP layer

by Josh Allmann for FFmpeg

Primary goal: improve receiver compatibility -X-Qt/quicktime depayloader -SVQ3 and QDM2 depacketizers -support Quicktime http tunnel mode -support RTCP/Bye as end-of-file Secondary goal: improve application integration -Provide an API to expose the RTCP layer (and the equivalent in RDT dialect) -Support subtitle streams -Make VideoLanClient, MPlayer, Xine use FFmpeg RTSP Tertiary goal: improve other protocols -RTMPE support for FFmpeg's native RTMP implementation