patch applied (cabal): Move the haddock code out into it's own module

[Duncan Coutts]

Tue Jul 31 11:34:10 PDT 2007  Duncan Coutts <duncan at haskell.org>
  * Move the haddock code out into it's own module
  It removes about 250 loc from Distribution.Simple

    M ./Cabal.cabal +2
    M ./Distribution/Simple.hs -215 +30
    A ./Distribution/Simple/Haddock.hs