patch applied (ghc): Simplify TcSimplify, by removing Free

[Simon Peyton Jones]

Thu Nov 23 09:16:02 PST 2006  simonpj at microsoft.com
  * Simplify TcSimplify, by removing Free
  
  For a long time TcSimplify used a three-way classification of constraints, 
  into 	Free
  	Irred
  	ReduceMe
  (see the data type WhatToDo).  In the new world of implication constraints,
  the Free case does not make so much sense, and I managed to elminate it
  altogether, thus simplifying the story somewhat.  Now WhatToDo has constructors
  	Stop
  	ReduceMe
  
  There should be no change in behaviour.
  

    M ./compiler/typecheck/Inst.lhs -5 +3
    M ./compiler/typecheck/TcRnTypes.lhs -1 +7
    M ./compiler/typecheck/TcSimplify.lhs -151 +124