SSU2: Fixes part 9

Fix length calculation to see if new token block will fit in session confirmed
Extend timeout after sending retry
Fix retx timer for sess req after sending token req
Remove dup call to confirmedPacketsSent()
Cancel ack timer when sending acks
Include intro key in firewalled addresses too
Use SSU2 version of ping packet for SSU2 peers
Reduce max padding
Log tweaks