wubloader/cutter/cutter
Mike Lang 066d10f94a Full cut: Support video transitions
We support all preset transitions in the xfade filter,
as well as a handful of "custom" ones we define.

We only support an audio cross-fade. We may want to support J and L audio cuts (switch audio
before/after the transition) later.
..
__init__.py cutter: Add initial outline
__main__.py cutter: Add initial outline
main.py Full cut: Support video transitions
upload_backends.py cuter: local upload backends: Use _ instead of - as replacement char