Random next track without changing playlist order.

[lwilletts]

Had this one in the mpc options section commented out for awhile to be implemented, but I talked to the one of the lead devs for mpv and he doesn't want to implement this option directly in mpv, so we'll have to fake do it in mpvc directly. Probably by storing a variable in a file somewhere.

[lwilletts]

Probably the best that can be done without adding the feature in mpv itself (which is unlikely) is a puesdo random where a number between 0 and playlist-count is picked and selected to play next.

[lwilletts]

This might tie into a playnext function I had in mind.. Looks like we're finally going to have to store a variable somewhere along with using observe_property to detect when the track gets changed.