Add a parent to the camera that follows a target to remove jitter

The parent is able to be smoothed via view interpolation, just like the client, while the camera can still be controlled by the user
Keep camera orientation constant when rover turns in third-person and top-down
Have manageTargetVisibility get the proper point of view when the target changed
Remove old commented-out code and simplified logic
Merge pull request #324 from virtual-world-framework/fix-camera-and-rover-jitter

Fix camera and rover jitter