Initial implementation, still needs control for when to show labels
Add a translucent white background for zoom labels
Scale zoom labels to fit within their associated item
Do not show a zoom label for RootItem
Remove the functionality to change an overlay's associated item(s)

This makes it easier to work with overlays
Add more functionality to overlay groups
Make zoom labels avoid overlap by hiding labels under top-level ones
Prepare zoom labels for a better way to handle overlaps
Implement a push-away strategy to avoid zoom label overlap

It is not the best solution, graphically, but it is very fast.
Speed up the reading of an overlay's associated items
Only show zoom labels of items visible in the main view
Add functionality to perform actions when the user is idle for 50 ms
Make the scene update when the user is idle
Remove the old NameOverlay, it has been replaced by Zoom Label Overlays