Use "Stop when inactive" timer in remaining time

[gampleman]

When seeding a torrent there is a timer that shows when will seeding complete based on the "Stop at ratio" setting. If the torrent is inactive however there will be a message "remaining time unknown" - this is however not true since the remaining time is a count down until the "Stop when inactive" timer finishes.

To illustrate: say I have a torrent set tot Stop at 2.0 ration and stop when inactive for 300 minutes. When seeding and the torrent becomes inactive it should show something like "4 hours 55 minutes remaining, seeding to 0 of 0 peers".

[livings124]

Transmission already does this when there's < 2 minutes remaining.