Reduced clutter in monadic code

+ Eliminated vairous ad-hoc coersion functions between specific monads 
  (IO, Err, IOE, Check) in favor of more general lifting functions
  (liftIO, liftErr).
+ Generalized many basic monadic operations from specific monads to
  arbitrary monads in the appropriate class (MonadIO and/or ErrorMonad),
  thereby completely eliminating the need for lifting functions in lots
  of places.

This can be considered a small step forward towards a cleaner
compiler API and more malleable compiler code in general.

src/compiler/GF/Grammar/Lockfield.hs

@@ -20,9 +20,9 @@ import GF.Infra.Ident
 import GF.Grammar.Grammar
 import GF.Grammar.Macros
 
-import GF.Data.Operations
+import GF.Data.Operations(ErrorMonad,Err(..))
 
-lockRecType :: Ident -> Type -> Err Type
+lockRecType :: ErrorMonad m => Ident -> Type -> m Type
 lockRecType c t@(RecType rs) = 
   let lab = lockLabel c in
   return $ if elem lab (map fst rs) || elem (showIdent c) ["String","Int"]