The queue and now-playing state only ever lived in the bot's memory,
so the dashboard had nothing real to show and a restart silently
wiped whatever was queued. Adds a musicrepo package and a syncState
call after every queue-changing action (play, skip, pause, volume,
stop, track end) that mirrors the current track and queue into
music_now_playing and music_queue.
No user-visible change yet, this is groundwork for the dashboard
queue/now-playing view.
FernandoJVideira
d6687879dd