Add wall1, wall2 and wall3
Add sample enemy spawner
Clean up DebugScene and add a basic enemy spawner to it
Add Enemy to EnemySpawner prefab
Add enemies destroying on bullet collision (the kill each other too at the moment)
ADD menu structure
Merge branch 'paavo' into dev

Conflicts:
	Assets/Scenes/DebugScene.unity
ADD GameLogic
Merge branch 'dev' into juho

Conflicts:
	Assets/Prefabs/Game/Enemy.prefab