Slow down ship.
Attempt to wrap position in vain.
Remove bounding circle.
Move wrapping logic to correct method.
Make ship go faster.
Add enemy sprite image.
Change asteroidsCategory to enemyCategory.
Create enemy node class.
Add physics for enemy node.
Increase mass and other characteristics.
Remove missile and enemy when they collide.
Make enemy glide more.
Auto add enemies to scene.
Generate enemies outside of view. *(Impulse vectors need fixing.)
Impulse enemies towards the view area.
Increase lateralThrust a bit.
Begin refactor: move consts to Constants.h
Use constants for scene size.
Use constants in randomPointOutsideView.
Add showBoundingShape constant.