Sync by setting SCNSceneRenderer's currentTime

Time updates from AVPlayer’s addPeriodicObserver, CAAnimations set to
use the SceneKit time.
View's layers resize without implicit animation

Actually, setting that property to false didn’t do the trick, but
setting duration to zero did.
Removed debugView
Arrows animate rotation as well as position
freeSceneLayer -> View for UI camera controls
CLDScene has startTime and finishTime

…and so this not a hard-coded magic number any more
Better 3D transformations, light, floor
View menu - camera positions

Animation here is broken.
Implicit animation on ;transform’ doesn’t work, which I thought it
should.
Using CABasicAnimation, my implementation doesn’t work properly here
either, can’t see why not.
Document Load+Save

[SCNScene read/write] doesn’t seem to work as expected, however.