Big ol refactor of how RUDP bootstrap occurs, so now we keep an estimate of the remote side's state as well as our own. We resend handshakes on the basis of what we think his state is as well as our own, so the curious case of both initial and second stage handshakes being sent and received can now occur. Furthermore, every path of code flow I can see is now protected by SYN cookies, and any attempts to flood or hijack connections should now be discarded i.e. security is restored. All unit tests pass, though we still have a partial cookie storm, something I am about to fix next.
Added a new "stop handshaking" handshake message, this prevents cookie resend storms and should restore full RUDP performance to previous levels.