ass: K&R formatting cosmetics
h264: Refactor ff_h264_draw_horiz_band() into a more generic function

Also add a NULL check and use frames directly.
svq3: use ff_h264_draw_horiz_band directly
mpegvideo: Refactor ff_mpeg_draw_horiz_band

Drop ff_draw_horiz_band because it's not used anywhere, add a NULL check.
er: move relevant fields from Picture to ERPicture

A new function is introduced to keep compatibility across the code.
h264: move relevant fields from Picture to H264Picture

A new function is introduced to support ERPicture.
h264: Replace mpegvideo-specific MAX_PICTURE_COUNT by private define
h264: Replace mpegvideo-specific MAX_THREADS by private define
h264: Remove MotionEstContext and move the relevant fields in H264Context
mpegvideo: move PICT_* macros into picttype.h

Also adjust the headers as needed.
mpegvideo: move MB_TYPE_* and IS_* macros to mbtype.h

Also adjust the headers as needed.
mpegvideo: remove h264-only fields
h264 does not depend on mpegvideo anymore
WIP: h264 with no struct avframe
alloc frames instead of unref
no reading strange things