This is only called from NTCPConnection.complete()
if there is more data, which is rare (never?)
so we don't need to check for dups or make _wantsRead a Set.
Was the peer UNreachable (outbound only) on any transport,
based on the last time we tried it for each transport?
This is NOT reset if the peer contacts us.
WATCHDOG -
Static variable in class net.i2p.router.util.EventLog
Send some data through the connection, or if there is no new data, this
may generate a packet with a plain ACK/NACK or CLOSE, or nothing whatsoever
if there's nothing new to send.
Pool of running threads which will transform the next I2NP message into
something ready to be transferred over an NTCP connection, including the
encryption of the data read.