Playlist transitions show a preview, and other improvements

Improvements

• Playlist transitions are shown as animated preview cards, so you can see what each one does before choosing it. The option previously called “None” is now “Instant”.
• A playlist with no screens assigned now shows a “Select screens for your playlist” prompt instead of an empty table, and explains how assignment by label works.
• The dashboard has a new typeface, which also loads faster than the one it replaces.