- Use splice() on Linux to move bytes around, it reduces CPU usage

- Add tcp_keepalive_* options to override timer values
- New options for HTTP CONNECT proxies: disclose_src, on_proxy_fail
- Add several options for graceful handling of connection pressure
- Fix several crashes & bugs

Version bump - v0.4

Version bump.

README: comment about UDP via OpenSSH & README.html

Release 0.1: TCP, basic UDP, Linux and OpenBSD support.