avconv: make -t insert trim/atrim filters.

This makes -t sample-accurate for audio and will allow further
simplication in the future.

Most of the FATE changes are due to audio now being sample accurate. In
some cases a video frame was incorrectly passed with the old code, while
its was over the limit.
avconv: make output -ss insert trim/atrim filters.

This makes output -ss sample-accurate for audio and will allow further
simplication in the future.
Merge commit 'a83c0da539fb07260310bc3b34056239d2b138b2'

* commit 'a83c0da539fb07260310bc3b34056239d2b138b2':
  avconv: make -t insert trim/atrim filters.

The filter insertion code is merged but disabled as it is buggy.
For example it fails in various ways when used with -s with some files.
Also the trimming is arguably less accurate than the default without
filters in some cases.
These issues should be fixed before auto inserting the filters,
until then the user can explicitly add a trim/atrim filter when one is
wanted.

Conflicts:
	Changelog
	ffmpeg.c
	ffmpeg_filter.c
	tests/ref/fate/bethsoft-vid
	tests/ref/lavf/aiff
	tests/ref/lavf/asf
	tests/ref/lavf/au
	tests/ref/lavf/avi
	tests/ref/lavf/dpx
	tests/ref/lavf/ffm
	tests/ref/lavf/gxf
	tests/ref/lavf/jpg
	tests/ref/lavf/mkv
	tests/ref/lavf/mmf
	tests/ref/lavf/mov
	tests/ref/lavf/mpg
	tests/ref/lavf/nut
	tests/ref/lavf/ogg
	tests/ref/lavf/pcx
	tests/ref/lavf/png
	tests/ref/lavf/rm
	tests/ref/lavf/ts
	tests/ref/lavf/voc
	tests/ref/lavf/voc_s16
	tests/ref/lavf/wav

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '8cd472d3f947a6233e7dc628f0dc71c74e62413a'

* commit '8cd472d3f947a6233e7dc628f0dc71c74e62413a':
  avconv: make output -ss insert trim/atrim filters.

Conflicts:
	Changelog
	ffmpeg.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
sws: share xyzgamma tables.

They are currently always constant and thus theres no point to
store them in the context.
This makes the context 16kb smaller

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>