how to register for an alert
todo
List of alerts
- torrent_finished_alert
- torrent_paused_alert
- torrent_checked_alert
- tracker_reply_alert
- tracker_announce_alert
- tracker_alert
- tracker_warning_alert
- storage_moved_alert
- torrent_resumed_alert
- state_changed_alert
- more: http://www.rasterbar.com/products/libtorrent/manual.html#alerts
