* block: added
- BLOCK_FLAG_CORRUPTED : signal corrupted data (do not use anymore BLOCK_FLAG_DISCONTINUITY in that case) - BLOCK_FLAG_PREROLL : mark this block to be decoded (no matter what). * ffmpeg, libmpeg2: support BLOCK_FLAG_PREROLL (ie disable frame dropping). * input: added ES_OUT_SET_NEXT_DISPLAY_TIME to ease the work for preroll (untested). * mp4: added support for CTTS table (pts, needed for h264+bframe). * decoders: for now handle discontinuity and corrupted block the same way.