Remove unused types.
Add missing command-line options to "revert".

All Committable commands have these options.
Seems I had forgotten to add them.  Would be
nice if these were not duplicated all over the
place.
Also delegate the diag() method.

This allows actions to write directly to
stderr if they want, but without using
one of the logging wrappers.
Allow the "quiet" option to supress all diag output.