Feature #571 - Special tag feedback

- The verbosity token 'special' now controls whether the feedback is provided
  when special tags are added to a task.
- Added new 'special' verbosity token documentation to man page.
- Added missing 'next' special tag to man page.
- Added new localized strings for describing special tags.

test/verbose.t

@@ -65,6 +65,7 @@ unlike ($output, qr/^\d+ tasks$/ms, '\'footer\' verbosity good');
 # TODO Verbosity: 'blank'
 # TODO Verbosity: 'header'
 # TODO Verbosity: 'edit'
+# TODO Verbosity: 'special'
 
 # Cleanup.
 unlink qw(pending.data completed.data undo.data backlog.data synch.key verbose.rc);