Log Message:
Update to 1.8.57

CHANGES:
1.8.57
    #6, add a preview of an API
    #331, improve parse error locations for literate Haskell
1.8.56
    Remove support for GHC 6.12 and below
    #317, tone down the void hint
    #16, match not . not (and reverse . reverse etc)
    Suggest <$> instead of fmap f $ ...
    Tweak some priorities, make >=> a warn and void an error
    #3, make top of the file ANN pragmas work
    #10, add a suggestion to use unlines
    #11, add a few hints about characters
    #8, add CHANGES.txt to the Cabal package