Make play queue persistent

[ToxicFrog]

The play queue appears to exist only in the browser's JS execution state, which means that if the browser gets restarted or even if the page gets reloaded, it evaporates. It would be nice to write it to PersistentStorage (or store it server-side and fetch it with a cookie, but that sounds like more work) so that it's a bit more durable.

[IrosTheBeggar]

I pushed a commit that adds this feature

[IrosTheBeggar]

The previous commit failed to get pushed. I made some updates and it's on the master branch now

[5HT2]

Hey, I don't see this commit on master, my play queue also disappears when I refresh the page.
This is my server version:

[5HT2]

Wait, unless you're referring to the "Live playlist" feature, which has been implemented and works. I just realized it exists, it seems to solve this issue but is a clunky workaround and there should probably be a default "Live Queue" that is enabled unless you start playing a normal playlist?

[5HT2]

See also: #436