Copyright-holder and year information is extracted from git log.
git history begins in 2005. So (C) from 1998..2005 is lost. Also some
(C) assignment of commits where the committer didn't use --author.
This preserves the stereo-ness of files that were imported or recorded in stereo.
ToDo (maybe someday): provide a disclosure triangle that exposes the individual channels in a multichannel region
Duplicate the remove_unsued_region action in the Session->Cleanup menu, for discoverability.
Region list should use the same Region actions as the canvas...
OK, now resolve the change in use-cases of Region List and Source List. tentative.
Rough-in remove_selected_sources (Delete in Sources list).
Column tweaks.
