- New "Size Map" feature that shows the resource size for selected assets in Content Browser
- Select assets in Content Browser, right click and choose "Size Map..." to show sizes for those assets
- Select actors and press Alt+Shift+M to show sizes of assets used by those actors
- Select assets in Reference Viewer, right click and choose "Size Map..." to show sizes for those assets
- Also added a new "Tree Map" general purpose Slate widget (STreeMap)
[CL 2521609 by Mike Fricker in Main branch]
