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

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