also fixes preview not playing if an entire set is restored
Implement structure for Editor HitObject composition
Add OnKeyDown override to OsuScreen
osu!catch hyperdash
Fix filename casing to compile on Linux
Fix crash when all beatmaps in a set are hidden
Fix DisposeTrack not working as expected
Also tidies up hyperdash state logic
Doesn't restrict direction yet. Also improves readability of fruit catch detection.
Migrate to C# 7