Split video by chapters (#158)

* New options `--split-chapters` and `--no-split-chapters`
* The output/path of the split files can be given using the key `chapter`
* Additional keys `section_title`, `section_number`, `section_start`, `section_end` are available in the output template
* Alias `--split-tracks` for parity with animelover/youtube-dl
* `--sponskrub-cut` and `--split-chapter` cannot work together

Closes:
https://github.com/blackjack4494/yt-dlc/issues/277
https://github.com/ytdl-org/youtube-dl/issues/28438
https://github.com/ytdl-org/youtube-dl/issues/12907
https://github.com/ytdl-org/youtube-dl/issues/6480
https://github.com/ytdl-org/youtube-dl/pull/25005

Rewritten from the implementation by: femaref and Wattux
https://github.com/Wattux/youtube-dl/tree/split-at-timestamps
https://github.com/ytdl-org/youtube-dl/pull/25005
https://github.com/femaref/youtube-dl/tree/split-track

yt_dlp/options.py

@@ -1183,6 +1183,17 @@ def parseOpts(overrideArguments=None):
         '--convert-subs', '--convert-subtitles',
         metavar='FORMAT', dest='convertsubtitles', default=None,
         help='Convert the subtitles to other format (currently supported: srt|ass|vtt|lrc)')
+    postproc.add_option(
+        '--split-chapters', '--split-tracks',
+        dest='split_chapters', action='store_true', default=False,
+        help=(
+            'Split video into multiple files based on internal chapters. '
+            'The "chapter:" prefix can be used with "--paths" and "--output" to '
+            'set the output filename for the split files. See "OUTPUT TEMPLATE" for details'))
+    postproc.add_option(
+        '--no-split-chapters', '--no-split-tracks',
+        dest='split_chapters', action='store_false',
+        help='Do not split video based on chapters (default)')
 
     sponskrub = optparse.OptionGroup(parser, 'SponSkrub (SponsorBlock) Options', description=(
         'SponSkrub (https://github.com/yt-dlp/SponSkrub) is a utility to mark/remove sponsor segments '