partial evaluator work

* Evaluate operators once, not every time they are looked up
* Remember the list of parameter values instead of recomputing it from the
  pattern type every time a table selection is made.
* Quick fix for partial application of some predefined functions.

src/compiler/GF/Grammar/Grammar.hs

@@ -16,7 +16,7 @@
 
 module GF.Grammar.Grammar (
         SourceGrammar, SourceModInfo(..), SourceModule, ModuleType(..),
-        emptySourceGrammar, mGrammar, modules, prependModule,
+        emptySourceGrammar, mGrammar, modules, prependModule, moduleMap,
 
         MInclude (..), OpenSpec(..),
         extends, isInherited, inheritAll,