Support ?style=plain on haddocks

Handler/Haddock.hs

@@ -50,6 +50,11 @@ getHaddockR slug rest
                 addExtra t = [t]
             req <- parseRequest $ unpack $ makeURL slug rest
             (_, res) <- acquireResponse req >>= allocateAcquire
+            mstyle <- lookupGetParam "style"
+            case mstyle of
+              Just "plain" -> respondSource "text/html; charset=utf-8"
+                            $ responseBody res .| mapC (Chunk . toBuilder)
+              _ -> do
                 doc <- responseBody res
                     $$ eventConduit
                     =$ concatMapC addExtra