Release Name: 0.9

Known issue: Mac OS Big Sur may report that VisuAlign needs keyboard input from other applications. This seems to be an inherent capability of the underlying technology, but VisuAlign doesn't actually use or need it, it's safe to select "Deny", we did the same when testing VisuAlign on Mac.

VisuAlign v0.9
- includes WHS Rat v4
- allows changing atlases via the Edit menu
- exports normal and "rainbow" (randomized colors) overlay images, useful for Allen labeling
- exports all overlays (previously only the nonlinear ones were generated)
- reworked keyboard handler for Mac, there is a chance that Delete/Backspace did not work so far, now they work.