Rill 0.3.1

Rill now uses mtorrent 0.6.1, which closes a torrent's uTP connections before the torrent stops. A torrent that is paused and resumed, or switched to downloading in order, keeps its port instead of moving to another one, and its peers learn at once that the connection has ended. A tracker that was already removed and a message a peer sends that mtorrent does not know are no longer reported as errors.