Fix TestCaseMultiScreen intermittent failures
Implement new difficulty calculator structure
Fix test dlls being loaded as actual rulesets (and failing)
Add "Grow" mod
Improve the build script (and move to a better location)
Add difficulty calculator tests
Fix nullref when entering multiplayer
Fix screen tests
Add support for the HitCircleOverlap property of legacy skins
Fix mouse cursor appearing prematurely during startup
Fix account creation overlay not working
Regressed with screen stack changes.
Fix MultiplayerTestCase not being abstract