add PushLuaFunction to functions

functions.go

@@ -302,3 +302,8 @@ func (s *State) GetAllLuaFunctions(names ...string) (map[string]*LuaFunction, er
 	}
 	return funcs, nil
 }
+
+// PushLuaFunction pushes a stored LuaFunction reference onto the stack
+func (s *State) PushLuaFunction(lf *LuaFunction) {
+	C.lua_rawgeti(s.L, C.LUA_REGISTRYINDEX, C.int(lf.ref))
+}