Make Ident abstract; imports of Data.ByteString.Char8 down from 29 to 16 modules

Most of the explicit uses of ByteStrings were eliminated by using identS,

	identS = identC . BS.pack 

which was found in GF.Grammar.CF and moved to GF.Infra.Ident. The function

	prefixIdent :: String -> Ident -> Ident

allowed one additional import of ByteString to be eliminated. The functions

	isArgIdent :: Ident -> Bool
	getArgIndex :: Ident -> Maybe Int

were needed to eliminate explicit pattern matching on Ident from two modules.

src/compiler/GF/Compile/Compute/ConcreteNew.hs

@@ -19,7 +19,6 @@ import Control.Monad(ap,liftM,liftM2,mplus,unless)
 import Data.List (findIndex,intersect,isInfixOf,nub,elemIndex,(\\))
 import Data.Char (isUpper,toUpper,toLower)
 import Text.PrettyPrint
-import qualified Data.ByteString.Char8 as BS
 import qualified Data.Map as Map
 --import Debug.Trace(trace)
 
@@ -80,7 +79,7 @@ resource env (m,c) =
 resourceValues :: SourceGrammar -> GlobalEnv
 resourceValues gr = env
   where
-    env = GE gr rvs (L NoLoc IW)
+    env = GE gr rvs (L NoLoc identW)
     rvs = Map.mapWithKey moduleResources (moduleMap gr)
     moduleResources m = Map.mapWithKey (moduleResource m) . jments
     moduleResource m c _info = do L l t <- lookupResDefLoc gr (m,c)
@@ -115,7 +114,7 @@ value env t0 =
     Vr x   -> var env x
     Q x@(m,f)
       | m == cPredef -> if f==cErrorType                -- to be removed
-                        then let p = identC (BS.pack "P")   
+                        then let p = identS "P"
                              in const # value0 env (mkProd [(Implicit,p,typeType)] (Vr p) [])
                         else const . flip VApp [] # predef f
       | otherwise    -> const # resource env x --valueResDef (fst env) x