Changed names of the class Tank private member functions that deal with intersections to avoid confusion with the class World private member functions that also deal with intersections (or collisions).

For example, class World and class Tank both had had a function called handleCollisions(). Now, there is World::handleCollisions() and Tank::handleIntersections(). The latter makes more sense for class Tank since that function really only does handle how tanks intersect with other tanks and blocks, rather than handling what happens when, for example, a tank collides with a projectile. Most importantly, the names are now less confusing.