Fix comment.
NavigationController: posView2D() Avoid crash if pos3d is not a list.
tiling.py: Removed _TileCache @synchronous decorator in favor of a context-manager solution that allows less fine-grained locking/unlocking. (significant optimization for large tilings)
tiling: Major optimization for the special but common case when all tiles are marked dirty at once.
For large volumes, the "fast path" for marking everything dirty results in ~20x faster response times for e.g. adding a new label class in ilastik.