UnicodeSyntax

GHC has [an extension called UnicodeSyntax](http://www.haskell.org/ghc/docs/7.2.1/html/users_guide/syntax-extns.html) that lets you use unicode symbols for various keywords in the Haskell syntax. It would be nice if I could automatically UnicodeSyntaxify code. This would involve adding the extension at the top of the module if not already there, and replacing all replaceable symbols with their unicode counterparts.