minor fix for direction of rotation for orbitControls
-overall cleanup and reorganization:
 * removed "showControls" attribute from three-viewer, now only in three-viewer-extra
 * removed deletion of objects in scene from three-viewer , now only in three-editor (makes more sense, nobody wants to
delete objects in a viewer, right?)
 * removed lots of clutter, and useless code from three-viewer , various smaller refacs as well