Unit Tests

- Many tests referred to 'synch_key.data', which is not the correct
  name.  It should be 'synch.key'.  This has no effect on the number
  of passing tests though.

test/args.2.t

@@ -72,7 +72,7 @@ ok (! -r 'pending.data'   &&
     ! -r 'completed.data' &&
     ! -r 'undo.data'      &&
     ! -r 'backlog.data'   &&
-    ! -r 'synch_key.data' &&
+    ! -r 'synch.key'      &&
     ! -r 'args.rc', 'Cleanup');
 
 exit 0;