Add per-torrent peer limit to "Transmission options"

[blackwind]

TransGUI currently offers a "global peer limit" setting, but neglects to offer the per-torrent limit setting available in Transmission. To me, at least, per-torrent is the more relevant setting, as I sometimes need to tweak it to boost speeds on public trackers. Would love to see it appear in TransGUI's "Transmission options" in a future release.

[blackwind]

Better yet, how about a two-part solution so this can be automated:

• Add Transmission's per-torrent peer limit to "Transmission options"
• Add a separate per-torrent peer limit ONLY for private trackers, along with a checkbox to toggle this functionality on and off, to "Application options"

Instead of defaulting the peer limit to the last used peer limit, when TransGUI opens a torrent with the private flag, if the private per-torrent option is enabled, the peer limit should default to the configured private per-torrent limit in TransGUI; otherwise, it should default to Transmission's per-torrent limit.