Improvements to the Zoom feature:
* Actor position and size within your level scales up and down
appropriately. The canvas size of the actor is scaled and its canvas
is told the Zoom number of the parent so it will render its own
graphic scaled correctly too.
Other features:
* "Experimental" tab added to the Settings window as a UI version of the
--experimental CLI option. The option saves persistently to disk.
* The "Replace Palette" experimental feature now works better. Debating
whether it's a useful feature to even have.
