changes to asteroids...

- speed (float) is replaced by velocity (vector)
- angle (float) is replaced by velocity (vector)
- creation of asteroids is more random (speed and direction is random), however
speed is clamped at a minimum of 20 pixels per second. (can change later when elastic collisions are implemented)
Merge branch 'master' of github.com:Kyrremann/snakes-in-space

Conflicts:
	snake-in-space/src/no/minimon/snakeinspace/Galaxy.java