[BT] Code style fix.
[BT] Show torrent status icons in Summary representation.
[BT] Don't requery status on status update.
[BT] Moved GetStringForState() to anonymous ns.
[BT] Refactored into GetStringForStatus().
[BT] Show error state for #1837.
[BT] Update torrent status on receiving torrent_error_alert for #1837.
[BT] Wrap status labels.
[BT] Provide info about error state in torrent state.

Finally closes #1837.