ib: added external send queue to workaround downtime

ib: added external send queue to workaround downtime
Workaround is because I couldn't find a correct way in ib to reconnect cleanly (with queue kept) when destination is unreachable.
When connection is broken, all internal queue contents are being destroyed and reconnects automatically.
An "external" send queue is kept until the connection is up again for a dest node.