Migrate osu to use the new difficulty calculator structure
Fix TestCaseMultiScreen intermittent failures
# Conflicts: # osu.Game.Rulesets.Taiko/Difficulty/TaikoLegacyDifficultyCalculator.cs
Implement new difficulty calculator structure
# Conflicts: # osu.Game.Rulesets.Osu/Difficulty/OsuLegacyDifficultyCalculator.cs
Fix test dlls being loaded as actual rulesets (and failing)
Add "Grow" mod
Improve the build script (and move to a better location)