Many updates to many scripts, scenes and prefabs in order to get the GUI working. Note to self: NEVER EVER forget the EventSystem again when making a prefab!
Merge branch 'Niels' into develop

Conflicts:
	Assets/Scenes/Random Generate Level.unity
	Assets/Scripts/RandomMaze.cs
Merge branch 'develop' of https://github.com/nversluis/TowerDefense into develop