Add GRF variable to use extra station names even when default names remain

src/openttd.cpp

@@ -471,6 +471,7 @@ static void ShutdownGame()
 	_game_load_tick_skip_counter = 0;
 	_game_load_time = 0;
 	_extra_station_names_used = 0;
+	_extra_station_names_probability = 0;
 	_extra_aspects = 0;
 	_loadgame_DBGL_data.clear();
 	_loadgame_DBGC_data.clear();