Changes by: Aleksey Nogin (nogin at cs.caltech.edu)
Date: 2005-12-21 18:59:18 -0800 (Wed, 21 Dec 2005)
Revision: 8343
Log message:

      Changing substT to be resource-based.
      
      Still need to do:
        - Implement {| subst |} resource annotations.
        - Annotate "a = b in int => a ~ b" and "a = b in nat => a ~ b" to make it so
          that hypSubstT/revHypSubstT would use squiggle rewriting instead of
          equality one for those types.