adding options: --package-conf and --no-user-package-conf

These command line options work just like the similar-named GHC flags.
They are useful when working with non-standard package databases.

Check.hs

@@ -18,13 +18,13 @@ import Types
 ----------------------------------------------------------------
 
 checkSyntax :: Options -> String -> IO String
-checkSyntax _ file = unlines <$> check file
+checkSyntax opt file = unlines <$> check opt file
 
 ----------------------------------------------------------------
 
-check :: String -> IO [String]
-check fileName = withGHC $ do
-    file <- initializeGHC fileName options
+check :: Options -> String -> IO [String]
+check opt fileName = withGHC $ do
+    file <- initializeGHC opt fileName options
     setTargetFile file
     ref <- newRef []
     loadWithLogger (refLogger ref) LoadAllTargets `gcatch` handleParseError ref
@@ -69,4 +69,4 @@ showSDoc :: SDoc -> String
 showSDoc d = map toNull . Pretty.showDocWith PageMode $ d style
   where
     toNull '\n' = '\0'
-    toNull x = x
+    toNull x = x