Bullet mostly done

Bullet is done, I think. It doesn't actually utilize the GameObject class, but I am fairly certain that it has the same functionality that extending GameObject would give it.

Edit 11/6/2014: The only methods that GameObject has and Bullet doesn't is the Direction enum and getDirection() (I use angles in radians instead, with getAngle()), getImage(),  and public setters for just about anything.
Also, the draw method has been changed so it can draw at angles and the constructor is a bit different.