‘QMutex::QMutex(QMutex::RecursionMode)’ is deprecated: Use QRecursiveMutex instead of a recursive QMutex [-Wdeprecated-declarations]

Related to #1190

Ideally we will have a gltf for each device, but in the meantime we could use a generic VR input device like https://poly.google.com/view/cUT5C1Krx7g or https://poly.google.com/view/0n5B6e5lYZe

XRTK - Mixed Reality Toolkit Feature Request

Is your feature request related to a problem? Please describe

The hand tracking implementation of XRTK already calculates curl strength for each finger and hand. Those values are not used for visualization yet though.

It would be nice to give the user a visual cue when grabbing stuff and curling fingers.

Relevant classes:

`HandJointVisualizer

engine-openvr-scene has the beginnings of a teleportation-style locomotion system. A long time ago, Valve and others discovered that fading to black before the teleport event minimizes locomotion-induced sickness. This will need to be integrated into the renderer as configurable post pass.