The camera orientation controls publish whether the map is tilted and the
camera's whole-degree heading instead of writing the buttons' attributes,
and answer tilt and north-up through the globe actions store. The new
GlobeCompass renders the heading, so a rotating camera re-renders only the
compass. The store drops an unchanged camera state and keeps each clear
owner's busy state, so the buttons show the shell that answers them: a
shell replaced by a newer one, or disposed mid-clear, leaves the live
shell's state alone, and an older shell that answers again shows its own.
createOwners gains owns() and ownerOf().