Dramatically improved efficiency of the dmr utility.

  The [dmr] utility has been made much more efficient, yielding a
  performance penalty of perhaps 10% instead of perhaps more than a
  factor of 30 (3000%).

Also made trivial comment changes and eliminated *saved-deep-gstack*,
which wasn't used.

After consulting with David Rager, I tried to ensure proper dmr
functionality for ACL2(p).