Merge branch 'master' into editor-timeline-rework
# Conflicts:
# osu.Game.Tests/Visual/TestCaseEditorComposeTimeline.cs
# osu.Game/Screens/Edit/Screens/Compose/Compose.cs
# osu.Game/Screens/Edit/Screens/Compose/Timeline/ScrollableTimeline.cs
# osu.Game/Screens/Edit/Screens/Compose/Timeline/ScrollingTimelineContainer.cs