[cvs-nhc98] patch applied (hat): Add a ' revert' keystroke to hat-trail. Used for reverting a lambda to

[Malcolm Wallace]

Mon Jun 21 08:51:16 PDT 2004  malcolm
  * Add a 'revert' keystroke to hat-trail.  Used for reverting a lambda to
  the expression which generated it, under the strict condition that the
  lambda is the direct and only result of the application.  Occasionally
  useful in combinator programs to make the trace more readable.

    M ./src/hattools/HatTrail.hs -2 +24