Add road layout change counter, add to road veh path caches

Update layout counter when non-leaf road bits are added or removed

src/misc.cpp

@@ -80,6 +80,7 @@ void InitializeGame(uint size_x, uint size_y, bool reset_date, bool reset_settin
 	_tick_skip_counter = 0;
 	_cur_tileloop_tile = 1;
 	_thd.redsq = INVALID_TILE;
+	_road_layout_change_counter = 0;
 	_game_events_since_load = (GameEventFlags) 0;
 	_game_events_overall = (GameEventFlags) 0;
 	_loadgame_DBGL_data.clear();