Fix reference counting when expiring peers.
Bump maxpeers to 125 like bitcoind.

It helps a lot if our max peers doesn't equal the max we'll try and open
outbound.
Don't send messages before handshake.

If we haven't handshaken with a peer don't send messages that are not
the handshake. Additionally don't queue up invs for sending, they'll
find out soon enough when they ask us what we know.