Updated Brad head (revamped new version) with facial expressions, added test scene

In the test scene, the BradHead prefab is parented to the head1_head rig bone of HuitreMagique's animated Patrick model, so it follows the head/neck animations nicely. Face poses are triggered by driving forward/backward with W/S.

We would soon need a headless player model (with animated head movements nontheless) for switching heads.