patch applied (ghc): Re-work the newtype-deriving support

[Simon Peyton Jones]

Fri Sep 22 21:05:05 PDT 2006  simonpj at microsoft.com
  * Re-work the newtype-deriving support
  
  The newtype deriving mechanism is much trickier to support than it
  seems at first.  Kevin didn't get it quite right when moving to FC,
  and I ended up re-writing quite a bit of it.  
  
  I think it's right now, but I have not yet tested it thoroughly.
  

    M ./compiler/iface/BuildTyCl.lhs -18 +19
    M ./compiler/typecheck/TcDeriv.lhs -34 +48
    M ./compiler/typecheck/TcEnv.lhs -11 +17
    M ./compiler/typecheck/TcInstDcls.lhs -69 +90
    M ./compiler/types/Coercion.lhs -36 +9