Use GhcModT everywhere and remove the GhcMod alias

Not doing this makes having GhcModT pretty pointless as users of the
library wouldn't be able to use custom inner monads as evey function for
dealing with GhcModT's would be constraint to (GhcModT IO) thus only
allowing IO as the inner monad.

src/GHCMod.hs

@@ -111,7 +111,7 @@ main = flip E.catches handlers $ do
         nArgs n f = if length remainingArgs == n
                         then f
                         else E.throw (ArgumentsMismatch cmdArg0)
-    res <- runGhcMod opt $ case cmdArg0 of
+    res <- runGhcModT opt $ case cmdArg0 of
       "list"    -> modules
       "lang"    -> languages
       "flag"    -> flags
@@ -152,7 +152,7 @@ main = flip E.catches handlers $ do
         hPutStrLn stderr $ "\"" ++ file ++ "\" not found"
         printUsage
     printUsage = hPutStrLn stderr $ '\n' : O.usageInfo usage argspec
-    withFile :: (FilePath -> GhcMod a) -> FilePath -> GhcMod a
+    withFile :: IOish m => (FilePath -> GhcModT m a) -> FilePath -> GhcModT m a
     withFile cmd file = do
         exist <- liftIO $ doesFileExist file
         if exist