gstrtpsession: Implement a number of feedback packet statistics

Fixes https://bugzilla.gnome.org/show_bug.cgi?id=711693
rtpjitterbuffer: Fix stats property field names and documentation
rtpmanager: fix Since markers

Should be next stable release series version
docs: get rid of 'Since: 0.10.x' markers

And some gtk-doc markup fixes.
rtspsrc: fix 'make check'

Fix generic/states check. Also, g_return_if_fail() is
not for internal state checking.
rtpjitterbuffer: avoid mapping the buffer

Reuse the parsed structure to get the timestamps.
qtdemux: Merge all the fourcc headers into one

Remove qtdemux_fourcc.h and ftypcc.h and put it all in fourcc.h
qtdemux: Sort fourcc declarations and remove duplicates
isomp4: Handle mp4s subpicture streams better.

Clean up the handling of mp4s streams. Use the generic esds
descriptor function to extract the palette, instead of hard coding
a wrong magic offset.

Add some more size safety checks when parsing ES descriptors, and
replace magic numbers with the descriptive constants that are already
defined.

Enhance dump output for stsd atoms.

Streams from both bug 712643 and historic bug 568278 now both work
correctly.

Fixes: #712643
rtptheoradepay: handle packets > 0xffff

Reorganize some things in the depayloader so that it can handle packets larger
than 16 bits.
Remove the size restriction on the payloader.
rtpvorbisdepay: handle packets > 0xffff

Handle input packet sizes larger than 16 bits in the depayloader.
Remove size restrictions on the payloader.
g_memmove() is deprecated

Just use plain memmove(), g_memmove() is deprecated in
recent GLib versions.

https://bugzilla.gnome.org/show_bug.cgi?id=712811
v4l2: clear cached caps on close

A different device with different caps may be used for the next open.

https://bugzilla.gnome.org/show_bug.cgi?id=712611
rtpjitterbuffer: pass downstream flowreturn to upstream

Fixes https://bugzilla.gnome.org/show_bug.cgi?id=712722
multifilesrc: Implement seeking in case of multiple images

https://bugzilla.gnome.org/show_bug.cgi?id=712254
matroskademux: Use GstVideoInfo helper to create caps for raw video

This way we do not miss mandatory fields in caps.
At the same time use the gst_pb_utils_get_codec_description helper to
get codec description.

https://bugzilla.gnome.org/show_bug.cgi?id=712328
qtdemux: Use GstVideoInfo helper to create caps for raw video

This way we do not miss mandatory fields in caps.
At the same time use the gst_pb_utils_get_codec_description
helper to get codec description.

https://bugzilla.gnome.org/show_bug.cgi?id=712335
videomixer2: Merge tag events to send them in collected.

Otherwise there were race conditions where we would send tags
on a flushing srcpad.

We have a test for that in GES, but this should be tested
systematically with harness in the future as I believe it
is useful for exactly that kind of cases.

https://bugzilla.gnome.org/show_bug.cgi?id=708165
matroskamux: correctly handle negative relative timestamps

... rather than scaling these as unsigned.

Fixes https://bugzilla.gnome.org/show_bug.cgi?id=712744

Based on patch by Krzysztof Kotlenga <pocek@users.sf.net>
rtpjitterbuffer: fix wake-up when new buffers come in after running empty

Spotted by 'gratias' on IRC. Probably introduced in recent refactoring.

https://bugzilla.gnome.org/show_bug.cgi?id=715039