Alternative RTMP implementation

Submitted by Jan Alexander Steffens @heftig

Link to original bug (#783354)

Description

Make.TV has been working on an alternative RTMP implementation in gst-plugins-bad, based on David Schleef's gst-rtmp. It still feels like a pile of hacks (with some pretty parts sticking out of it), but we think it's already pretty usable.

It features: rtmp2sink/src as drop-in replacements for the existing rtmpsink/src, no segfaults when stopping (bug 729099), handling ping and stats messages, adobe-style auth.

Major things that are known to be missing are: Automated tests, documentation, support for rtmpt/rtmps/rtmpe, a server implementation, post-start command handling, not depending on flvmux and flvdemux.

The code is available at
https://github.com/heftig/gst-plugins-bad/tree/rtmp2/gst/rtmp2 . It's
branched off 1.12.0; as of today 1.12 and master still merge in fine.