Add environment variable to ignore types from ICG processing #535

Added a new environment variable TRICK_ICG_IGNORE_TYPES.  Class/struct/enum
types found in this semicolon delimited list will not have attributes written
out.

trick_source/codegen/Interface_Code_Gen/main.cpp

@@ -164,6 +164,7 @@ int main(int argc, char * argv[]) {
 
     PrintAttributes printAttributes(attr_version, hsd, cs, ci, force, sim_services_flag, output_dir);
 
+    printAttributes.addIgnoreTypes() ;
     // Create new class and enum map files
     if (create_map) {
         printAttributes.createMapFiles();