Rocket Rescue 0.1.0

This is probably the biggest change so far in a single update.  New rocket, new asteroid generator, and a high score!

Changelog:

• New rocket based on the Apollo Command Module
• Removed walls
• Replaced asteroid patterns with random (seeded) asteroid placement
• Replaced old exhaust particle effects
• Added start screen with controls
• Added score
• Added velocity
• Added death screen
• [REDACTED]
• Refactored system that generates new asteroids so it now happens just in time
• Removed checkpoints (temporarily)

I guess that's all.  Leave a comment if you find the secret feature and share your high scores!