Declare Barrage as a Firefox application for torrent and magnet links

[axelsimon]

Is your feature request related to a problem? Please describe.
It would be nice to be able to click magnet: links and have that open directly in Barrage.

Webmails can do that for mailto: links for instance.

Describe the solution you'd like
Click magnet links or torrent links, Firefox checks with you if want to open that link in an app, you pick Barrage, done.
Future magnet links on the same website will automatically open in Barrage.

Describe alternatives you've considered
Can't think of any, right now.

Additional context
I don't know how an application can register themselves with Firefox, but in Firefox itself you can expose the menu for choosing an application for managing magnets or torrent links by adding entries in about:config:
network.protocol-handler.expose.magnet = false
network.protocol-handler.expose. torrent = false