Feature request: a %duration% tag for each album

[fivefivefiver]

Like the title says - for every album in cover flow, expose a %duration% variable so that I can display the album's duration in the cover flow preview (and other places, too, since Foobar is missing this completely).

Even if it's not a variable available outside coverflow, just being able to see the album duration in the title format string would be a massive help.

Thanks!