Sort queue on track number if available

[jeremypw]

Fixes #767

[zeebok]

Out of curiosity, if you were to open multiple albums at once via Files how does this handle the ordering? Currently if I multi-select album folders and use Open In Music, the songs are not in order within the album, but they are grouped by album. Would be cool if it grouped by album and in album order!

[jeremypw]

@zeebok I agree the ordering of the queue needs to be more sophisticated/customizable (see #255, #767, #779). This is just a start.