Changes by: Aleksey Nogin (nogin at cs.caltech.edu)
Date: 2006-03-02 00:12:57 -0800 (Thu, 02 Mar 2006)
Revision: 8818
Log message:

      Use the nilSqequal lemma ( l = [] in T List --> l ~ [] ) in *substT tactics
      (to avoid unnecessary wf subgoals).