patch by Stefano Sabatini, stefano.sabatini-lala poste it

Originally committed as revision 13005 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 12399 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 11711 to svn://svn.ffmpeg.org/ffmpeg/trunk

Since decoding is doing from the end and aligned by 16
previous code worked correctly only when picture height was dividable by 16,
otherwise it provides garbage in top lines and truncates bottom.
New code adjusts data[] pointers taking in account alignment issue.

Originally committed as revision 10727 to svn://svn.ffmpeg.org/ffmpeg/trunk

Patch by Vladimir Voroshilov (voroshil - gmail - com)

Originally committed as revision 10617 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 9169 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 9071 to svn://svn.ffmpeg.org/ffmpeg/trunk