[GHC] #4232: Finish and merge new typechecker branch

[GHC]

#4232: Finish and merge new typechecker branch
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    Reporter:  igloo                    |        Owner:  simonpj     
        Type:  bug                      |       Status:  new         
    Priority:  high                     |    Milestone:  6.14.1      
   Component:  Compiler (Type checker)  |      Version:  6.13        
    Keywords:                           |     Testcase:              
   Blockedby:                           |   Difficulty:              
          Os:  Unknown/Multiple         |     Blocking:              
Architecture:  Unknown/Multiple         |      Failure:  None/Unknown
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 Finish and merge new typechecker branch

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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4232>
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