Improve chopper ack/retransmit reliability
It has been reported that Stegotorus can not reliably surf the web and it's most likely a problem with ack/retransmit feature.
One known problem is that in presence of ACKs, ST needs to wait until it has sent and received ACK(FIN) before closing a circuit, not until it has sent and received FIN.
The problem with this bug is that it can not be reproduced reliably but the bad proxy would hopefully solve this issue.