[Feature Request] Add option to omit scenes

[hyuri]

I imagine this is already planned, but I couldn't find any issues associated with it, so, to be sure, here we go.

Add option to omit a scene, which would mean the scene gets hidden from view and is not printed.

In terms of UI, I think the scene should be collapsed into an "OMITTED" line (that's what Final Draft and Fade In Pro do), perhaps also preceded by an arrow we can click on to view the contents of the omitted scene, that would then look faded until we un-omit it, and followed by a gear icon with the option to un-omit it.