Velocity fix and more

I've had a fix for the issue where the velocity of the ship was kept after a collision with an asteroid, rather than it bouncing or something. There was also a bug where, if you beat the game and wanted to play again, the game would crash rather than taking you back to the beginning.

I do have some ideas to improve things a bit, and I've been asked to add something like a timer for speed running, but then I'd also have to seal up the (intentional) gaps in the asteroids. There was also originally a feature planned, whereby you can pick from one of three loadouts in the beginning, which I may add eventually, but right now, I'm trying to focus on other projects.