Add collision detection on ships.

[markcornwell]

Need to detect when ships collide with one another. Also will need it when we include missiles.

[markcornwell]

Jeffrey Thompson posted a pretty algorithm to tell if a point falls inside a triangle.

http://www.jeffreythompson.org/collision-detection/tri-point.php

[markcornwell]

Time to implement collision detection. Having implemented missile fire animation, we need to have ships destroyed (or take damage!) when hit by missiles.

[markcornwell]

Ships get destroyed by missiles now. No explosion, they just blink out of existence like they were disintegrated.