Wave Update (Devlog #3)

This update adds a wave system with a 30 second wait period between each wave (which can be skipped if you are ready). Each wave contains more zombies which will become faster as the waves progress. All zombies now have a random speed that ranges from the old base speed to the old base speed + the current wave / 5.

The UI has been developed massively behind the scenes, however I have not yet implemented it fully in the shop. The UI now opens and closes how you would expect it to, but the contents have not been added yet. More work must first be done to the UI system.