The new version, merged into the RTP stream output, is supposed to be
better than the old one, except for two dropped features:

 - non-standard RAW/RAW/UDP and MP2T/H2221/UDP RTSP Transports, and
   x-playNow RTSP header: the only vague specification of this that I
   could find is this 10-year-old draft:
   http://www-rn.informatik.uni-bremen.de/ietf/mmusic/47/id/draft-sheedy-mmusic-rtsp-ext-00.txt
   They provide support for broken Amino STBs.

 - client number limiting: not sure how pertinent that is and if it
   would be the right way to implement/port it

If you think it's a problem to drop these features, speak now.
Ultimately the goal is to get rid of the old code (after the next major
release?)

Closes #568