— procedure: delete-coot-backup-files action-type

— procedure: clear-backup-gui

Return #t or #f depending on if the GUI dialog was shown (it isn't show if there are no files to delete).

— procedure: clear-backups-maybe

Return a status, #f or #t, did the GUI run?

Note that clear-backup-gui returns either #t or #f too.

If this function returns #f, then coot_real_exit() just exits with coot_real_exit(). Otherwise we wait for the GUI.