[haddock] #93: Move lexing and parsing of Haddock comments into Haddock

[haddock]

#93: Move lexing and parsing of Haddock comments into Haddock
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Reporter:  waern  |       Owner:       
    Type:  task   |      Status:  new  
Priority:  major  |   Milestone:  2.6.0
 Version:  2.4.1  |    Keywords:       
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 Currently, GHC does lexing and parsing of Haddock comments. This was
 decided so GHC could rename the Haddock comments during its renamer phase.
 Since it's possible to access the renaming environment from the GHC API,
 we could do the renaming in Haddock instead, which would enable us to move
 lexing and parsing of Haddock comments into Haddock. The advantage is that
 we don't have to do development to GHC in order to make changes to these
 components.

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Ticket URL: <http://trac.haskell.org/haddock/ticket/93>
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