Add config option to auto exit after save, and disable successful save popup

[eharris]

The result popup is really annoying, because it prevents you from closing the program unless you first click on the popup to dismiss it.

I would prefer to only be notified if something went wrong, not on success. Even better would be an auto-close option that once a save was successful would automatically close the program, since that removes two interactions that are currently required (close the popup and exit) which would speed up my workflow considerably.

Fixing the result popup not to require interaction is already mentioned in #76, but since that ticket is closed and the problem remains, I'm creating this ticket.

[Okxa]

I agree, this is essential in some workflows.

I have a shell script opening the latest screen capture in this editor for quick cuts. So far this has been the fastest ffmpeg based editor for this use case, and only thing hindering my editing process is the popup and no auto close.

Another thing to speed things up would be to automatically allow opening the save folder on exit/save.