Extern C support for registering function overloads

src/UserData/UserDataFunction.cpp

@@ -13,5 +13,11 @@ namespace Porygon::UserData{
             t->RegisterOption(opt);
             return t;
         }
+
+        void RegisterFunctionEvalValueOption(const GenericFunctionEvalValue* val,
+                const Evaluation::EvalValue* (*func)(void*, const ScriptOptions*, const EvalValue* [], int ), void* obj){
+            auto opt = new UserDataFunction(func, obj);
+            val->RegisterOption(opt);
+        }
     }
 }