patch applied (ghc): Implement -X=GADTs and -X=RelaxedPolyRec

[Simon Peyton Jones]

Wed Jun 20 09:33:59 PDT 2007  simonpj at microsoft.com
  * Implement -X=GADTs and -X=RelaxedPolyRec
  
  Two new -X flags, one for GADTs and one for relaxed polymorphic recursion
  
  This also fixes a rather confusing error message that the Darcs folk 
  tripped over.
  

    M ./compiler/typecheck/TcBinds.lhs -9 +9
    M ./compiler/typecheck/TcPat.lhs -5 +9
    M ./compiler/typecheck/TcTyClsDecls.lhs -3 +4
    M ./docs/users_guide/flags.xml -7 +20
    M ./docs/users_guide/glasgow_exts.xml -2 +2