struct variable type checking, refactoring to avoid circular dependencies

ubcc.cabal

@@ -25,14 +25,16 @@ source-repository head
 
 library
   exposed-modules:
-      Data.String.Ubc.Parse
-      Data.String.Ubc.Parse.FileScope
-      Data.String.Ubc.Parse.Language
-      Data.String.Ubc.Parse.ParserState
-      Data.String.Ubc.Parse.Scope
-      Data.String.Ubc.Parse.Struct
-      Data.String.Ubc.Parse.StructScope
-      Data.String.Ubc.Parse.StructVariable
+      Ubc.Parse
+      Ubc.Parse.Data.Struct
+      Ubc.Parse.Language
+      Ubc.Parse.ParserState
+      Ubc.Parse.Scope
+      Ubc.Parse.Scope.FileScope
+      Ubc.Parse.Scope.StructScope
+      Ubc.Parse.Struct
+      Ubc.Parse.Types
+      Ubc.Parse.VariableType
   other-modules:
       Paths_ubcc
   autogen-modules: