Minor Update: CPU reduction, undo/redo UI, continuous sky grabbing — SculptrVR Steam update #60416

This minor update has significant back-end performance improvements, and a few UI improvements: World size is now (mostly) independent of CPU usage! Sculpting at large scale over destroyed detail no longer reduces performance. Undo/Redo are now performed by clicking buttons on the color palette instead of hidden swipe gestures. Sky grabbing can no longer be interupted by the floor or voxels. With these performance improvements out of the way, we're now plowing head-first into multiplayer! We hope to have that ready very soon.