PlanarControls offers ergonomic camera controls for the planar mode : drag, pan, orbit,
zoom and animated expression to smoothly move and orient the camera.

Modified planar example to use these controls
Update contributors

Modifications following peppsac review :
-all external variables are now within the class, this allows to
instanciate more than one controller.
-clamp01 function removed, using THREE clamp instead.
-various style modifications (separator removed, const array format...)

update() uses mainloop's deltatime, no longer call camera.update()
this.camera.position replaces this.position

…d of S (used for picking)