lavc decoders: properly initialize AVFrame.
lavc: allow decoders to override frame parameters.
lavc: limit maximum number of channels to 63

This is the most that can be represented with the current channel layout
system. This limit should be raised/removed when a better system is
implemented.
lavc: make up a fake frame channel layout when there is no real one.

This should ensure that a valid channel layout is always set on a frame,
until a better solution is implemented.
mpegvideo: drop vismv code

It has been broken for over a year without anyone complaining or
noticing, thus proving that nobody ever uses it.
avconv: convert to new refcounted AVFrame API
avplay: switch to new refcounted frames API

Remove now unused cmdutils get_buffer() implementation.
avserver: don't set deprecated options.
lavc: stop setting AVFrame.motion_subsample_log2

It is not used inside lavc anywhere and now it makes no sense to export
it.
AVFrame: deprecate all now unused fields
lavc: postpone the removal of request_channels API.

Its replacement is still not ready.
Add the bumps and APIchanges entries for reference counted buffers changes.
Replace some forgotten instances of PIX_FMT_* with AV_PIX_FMT_*.
Replace remaining includes of audioconvert.h with channel_layout.h
eamad: allocate a dummy reference frame when the real one is missing

CC:libav-stable@libav.org
ffv1: fix calculating slice dimensions for version 2

It got broken in 0f13cd3187192ba0cc2b043430de6e279e7b97c3.

CC:libav-stable@libav.org
FATE: enable multiple slices in the ffv1 vsynth test

This allows us to test the slice threading code.
tty: set avg_frame_rate.

The container does not store any timestamps and is CFR-only.
xxan: fix invalid memory access in xan_decode_frame_type0()

The loop a few lines below the xan_unpack() call accesses up to
dec_size * 2 bytes into y_buffer, so dec_size must be limited to
buffer_size / 2.

CC:libav-stable@libav.org
roqvideodec: fix a potential infinite loop in roqvideo_decode_frame().

When there is just 1 byte remanining in the buffer, nothing will be read
and the loop will continue forever. Check that there are at least 8
bytes, which are always read at the beginning.

CC:libav-stable@libav.org