avplay: add support for seeking to chapter marks
lavf: rewrite the av_interleaved_write_frame() doxy

Remove some vague / incorrect statements and make the text more specific
and less confusing.
lavf: rewrite the av_write_frame() doxy

Remove some vague / incorrect statements and make the text more specific
and less confusing.
lavf: add some basic documentation of the muxing process
lavf: extend / improve the AVFormatContext doxy
build: fix examples compilation when EXESUF is not empty

Due to a wrong substitution doc/examples is not added as a prerequisite
for the objects of the example programs. This results in compiler error
due to the non-existing output directory.

Bug-Id: 636

Signed-off-by: Janne Grunau <janne-libav@jannau.net>
Merge commit 'b36bc81ccaa2fc85dc4bae7dc546c71e8833573d'

* commit 'b36bc81ccaa2fc85dc4bae7dc546c71e8833573d':
  avplay: add support for seeking to chapter marks

Conflicts:
	doc/ffplay.texi
	ffplay.c

ffplay uses pageup/down for seeking by +-10min
thus this use of the keys conflicts.
The merge thus uses them to seek to chapters when there are some or
+-10min when there are not

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit 'ad7f2b69a546ec65ef6b11e1a0fd58e6bb66bc4b'

* commit 'ad7f2b69a546ec65ef6b11e1a0fd58e6bb66bc4b':
  lavf: rewrite the av_interleaved_write_frame() doxy

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '4c750599509c3973afbe2850953a1fb963f696e5'

* commit '4c750599509c3973afbe2850953a1fb963f696e5':
  lavf: rewrite the av_write_frame() doxy

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '54f7e79d4706a8343dad1d8da51b7d3d3b2cd3b2'

* commit '54f7e79d4706a8343dad1d8da51b7d3d3b2cd3b2':
  lavf: add some basic documentation of the muxing process

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '18c896be3d8e926ef806e7de29c4a168d7763389'

* commit '18c896be3d8e926ef806e7de29c4a168d7763389':
  lavf: extend / improve the AVFormatContext doxy

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge remote-tracking branch 'qatar/master'

* qatar/master:
  build: fix examples compilation when EXESUF is not empty

Merged-by: Michael Niedermayer <michaelni@gmx.at>
avformat/concatdec: pass the interrupt callback on

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