avformat/mov: decode compilation metadata

This flag is known as 'Part of a compilation' in Apple iTunes.

Signed-off-by: Peter Ross <pross@xvid.org>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avformat/movenc: encode compilation metadata

Fixes ticket #2960.

Signed-off-by: Peter Ross <pross@xvid.org>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avformat/id3v2: decode compilation metadata

Described http://id3.org/iTunes%20Compilation%20Flag

Signed-off-by: Peter Ross <pross@xvid.org>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>