Changed performance error on safari
Correct background image resizing
Corrected background shift on horizontal movement.
Resized image to exactly match the game surface.
Added brake / reverse on the ship.
Bit of refactoring on background calculations and ship braking
Top bottom background shifts done; corners remain
Background issue solved
Asteroids are now correctly displayed when the camera is on a corner
Added collisions between asteroids
Simple rebound mechanism
Improved collision physics
First pass for shooting down asteroids