Gun functioning

Gun no longer able to cross right/left sides. Shooting functional.
Bullet movement functional. Collision functional.
Merge branch 'A-Star-Testing' of https://github.com/arugl/Per6-Liang-Ma-SnakeHunting into A-Star-Testing

Conflicts:
	SnakeHunter/Gun.pde
	SnakeHunter/SnakeHunter.pde