Add mkv chapter cutter

[RyougiKukoc]

1. Input includes video stream of *vc formats, audio streams of flac format, and subtitles of pgs format. Chapters must be aligned with pts.
2. Use mkvmerge to cut video and subtitles.
3. Use ffmpeg to re-encode flac according to chapter.
4. Specify chapter index when input, "all chapter mode" should be allowed.
5. Migrate audio info (at least language tag and track name) into the new mkv.
6. Judge the head/tail chapter, especially the tail chapter.
7. Output filename should append extra info before discription (BD WxH ...).

[RyougiKukoc]

Judger detail of item 7:

filename = os.path.splitext(os.path.basename(filepath))[0]
if filename.endswith(')'):
    sq = filename.split('(')
    sq[-2] += f'.{idx}'
    new_filename = '('.join(sq)
else:
    new_filename = filename + f'.{idx}'

[RyougiKukoc]

This function is released at 509499b