Explanation: The upgrade to Liquidsoap 2.0 now means that Liquidsoap itself can hold more than one song in its upcoming queue, which allows us to make functionality like "skip song" work as expected for the first time, but also meant that our previous methods of tracking what songs were and weren't queued didn't work well at all. This overhauls the queue builder by adding a new "is_played" status to each queue entry and treating the entire "unplayed" queue (whether sent to the AutoDJ or not) as the "upcoming" queue, fixing a number of issues.