v0.5.9

This one is mostly about the now-playing view: the app can take its colours from the album art, and the scroll wheel now works as a volume control.

New features

• Adaptive theme: a new Themes setting (off by default) that takes the accent and surface colours from the playing track's cover, crossfading on each track change.
• Scrolling over either volume slider, or over the big artwork in the now-playing view, changes the volume 5% per notch.

Bug fixes

• On Windows, long lists no longer stutter and drift on their own after you stop scrolling.
• Collaborative playlists: you can now remove the tracks you added. Rows also show who added them, the header carries a "Collab" badge, and the "saved to" marks stay accurate.