Level transitions

We have a couple of different door tiles in our tile set that can be used to allow the player to exit the current map and enter a new one. In Chapter 8, Gemstone Hunter—Put on your Platform Shoes, we indicated that marking a square with a code in the format T_M_X_Y would indicate that the square contained a transition to map number M at location (X, Y). We will implement this functionality by modifying the Player class.