Bugfix: OcclusionGroups - fix NRE when moving out of group with a sleeper
- replaced with a IsVisibleFromFar check
- also reworked teleportation logic via IsVisibleFromFar, as that's more correct
- also IsVisibleFrom range check was wrong, so fixed that
Previous code relied on subscriber to check if move-out-of-bounds occurred, but sleepers don't have a subscriber, so it NREed
Tests: moved away from a cell with a sleeper, checked internal state