Basically, when using the third person camera in HMD mode. If the controllers are shown.
They should be shown in front of the users camera, not in front of the users avatar.
To accomplish this, two new faux joint indices are introduced.
CAMERA_RELATIVE_CONTROLLER_RIGHTHAND_INDEX and CAMERA_RELATIVE_CONTROLLER_LEFTHAND_INDEX.
These joint indices can be used for Overlay parenting. (But not for entity parenting because they are not transmitted over the network).
They can also be queried for by using the MyAvatar.getAbsoluteJointRotationInObjectFrame() call.
These new indices are now used by the controllerDisplay.js for the hand controller rendering.
They are also used by system/libraries/controllers.js as the origin for hand controller grabbing and interaction lasers.
