TestPhysicsRayCast uses a ray that's too short

[stephengold]

Despite the name, PhysicsSpace.rayTest() uses a "ray" of finite length, what mathematicians call a line segment.

TestPhysicsRayCast currently uses a "ray" with length=1. For the test model used, this is too short to reach the model from the initial camera position.

For TestPhysicsRayCast to be a useful and convenient test, the ray needs to be much longer, perhaps 50 world units.

[stephengold]

Note: with the longer ray, the test seems to work for JBullet, but not Native Bullet. This is due to an unrelated issue (#887) with visualizing scaled mesh shapes in jme3-bullet.

[stephengold]

Fixed in 'master' branch.