qtdemux: Raw buffer DTS should always be CLOCK_TIME_NONE
qtdemux: Fix compilation
session: pass data to remove func

Pass the data to the remove function because we are going to deref it when there
is pli or fir.
session: handle Retransmission event and schedule NACK

Handle the retransmission event from downstream and use it to schedule a NACK
request.
source: add methods to register NACK

Add a method to register a missing packet for an ssrc along with
methods to get the missing packets and clear them.
session: add NACK feedback in RTCP
rtpvp8depay: mark key frames and delta frames properly

https://bugzilla.gnome.org/show_bug.cgi?id=705550
matroskademux: Don't print warnings during flushing and stop as soon as possible

https://bugzilla.gnome.org//show_bug.cgi?id=705442
avidemux: send proper stream_start event

https://bugzilla.gnome.org//show_bug.cgi?id=705449
videomixer: bundle private copies of videoconvert code.

Ideally, this would be part of libgstvideo.
Prefixes videoconvert symbols with videomixer_.
videomixer: don't send reconfigure event when formats or PAR are different.

It is racy with multiple pads.
videomixer: add colorspace conversion.