Fix viewport in manual vr distortion path

The viewport now has 1:1 ratio matching the canvas size.
Use old manual vr distortion path in dualcam example (for Cardboard)

When the 'Toggle VR' button is pressed and now WebVR hmd is found, it renders the scene fullscreen with the manual vr distortion path.
With this, you can use this example to watch VR on a Cardboard with a smartphone.
Fix small inconsistencies in Manipulators
Optimize Quaternion multiplication

Allowing mult(a, b, a) to do [a*b] and store in a
Add DeviceOrientation to eventProxy
Add FirstPerson Manipulator for DeviceOrientation
Add Orbit Manipulator for DeviceOrientation
Add Orbit Manipulator for Oculus