Show duration of playlists
As described in #40 (closed), this PR adds the total duration of a playlist to every relevant spot in the dashboard, and pre-warns the user if the playlist they select for a given timeslot is too long/too short.
As described in #40 (closed), this PR adds the total duration of a playlist to every relevant spot in the dashboard, and pre-warns the user if the playlist they select for a given timeslot is too long/too short.