serialize

Serialize the node id and the live routing-table nodes into a bencoded blob the platform can persist and pass back to restore on the next start. This is the KiteTorrent analogue of libtorrent's dht_state save (save_state, dht_settings). Only the id and (host, port) of every live node is kept; ids are re-confirmed on the next bootstrap, so a stale node simply fails to answer and is dropped.