use quaternions to implement panorama rotation freely

[jasonChen1982]

use quaternions rotation to optimize SphereWorld's drag rotation, quaternions multiply a delta quaternions.

[jasonChen1982]

pseudo code like follow:

sphereWorld.on('drag', delta => {
  const dq = getDeltaQuat(delta);
  sphereWorld.quaternions.multiply(dq);
});

implement like this way can avoid rotation lock.

[Oldsooh]

Just take a look~