Add mania selection blueprint testcases
Separate note selection mask into a note piece
Move scroll algorithm to a more global location
Fix mania selection blueprint sizing
Add framework for private messaging support
Implement IScrollAlgorithm.TimeAt()
Make scroll algorithms not tied to drawable hitobjects
Hide seekbar when no song is playing
Make SliderPath immutable
Update framework and resources
Change .idea ignore rules to not ignore run configurations
# Conflicts: # osu.Game/Tests/Visual/SelectionBlueprintTestCase.cs