e284a8878b
* Include the most recent ACKs with packets, rather than only sending an
ack exactly once. SSU differs from TCP in this regard, as TCP has ever
increasing sequence numbers, while each message ID in SSU is random, so
we don't get the benefit of later ACKs implicitly ACKing earlier
messages.
* Reduced the max retransmission timeout for SSU
* Don't try to send messages queued up for a long time waiting for
establishment.