Support different output formats (new `export-scenes` command)

[Breakthrough]

To ease the transition to supporting #156 and #323, the next version should include a new export-scenes command that will support multiple output formats. Ideally the command should be allowed to be specified twice, and allow some different output formats, e.g.:

scenedetect -i video.mp4 export-scenes --format=csv

scenedetect -i video.mp4 export-scenes --format=edl

scenedetect -i video.mp4 export-scenes --format=fcp

scenedetect -i video.mp4 export-scenes --format=qp

Open tracking bugs:

• [ ] FCP - #156
• [ ] Chapter Formats - #323
• [ ] QP - #388

References:

EDL reference: https://github.com/mpv-player/mpv/blob/master/DOCS/edl-mpv.rst Chapter formats: https://github.com/rigaya/NVEnc/blob/master/NVEncC_Options.en.md#--chapter-string https://gist.github.com/schtritoff/8e0105060cb07c118863867429473830 https://github.com/Mtillmann/chaptertool/issues/1