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.

Language/Haskell/GhcMod/Logger.hs

@@ -34,7 +34,7 @@ newtype LogRef = LogRef (IORef Builder)
 newLogRef :: IO LogRef
 newLogRef = LogRef <$> newIORef id
 
-readAndClearLogRef :: LogRef -> GhcMod String
+readAndClearLogRef :: IOish m => LogRef -> GhcModT m String
 readAndClearLogRef (LogRef ref) = do
     b <- liftIO $ readIORef ref
     liftIO $ writeIORef ref id
@@ -50,9 +50,10 @@ appendLogRef df (LogRef ref) _ sev src style msg = do
 -- | Set the session flag (e.g. "-Wall" or "-w:") then
 --   executes a body. Logged messages are returned as 'String'.
 --   Right is success and Left is failure.
-withLogger :: (DynFlags -> DynFlags)
-           -> GhcMod ()
-           -> GhcMod (Either String String)
+withLogger :: IOish m
+           => (DynFlags -> DynFlags)
+           -> GhcModT m ()
+           -> GhcModT m (Either String String)
 withLogger setDF body = ghandle sourceError $ do
     logref <- liftIO $ newLogRef
     wflags <- filter ("-fno-warn" `isPrefixOf`) . ghcOpts <$> options
@@ -65,7 +66,7 @@ withLogger setDF body = ghandle sourceError $ do
 ----------------------------------------------------------------
 
 -- | Converting 'SourceError' to 'String'.
-sourceError :: SourceError -> GhcMod (Either String String)
+sourceError :: IOish m => SourceError -> GhcModT m (Either String String)
 sourceError err = do
     dflags <- G.getSessionDynFlags
     style <- toGhcMod getStyle