Lwt and Mirage-friendly library wrappers

[cfcs]

Ideas so far:

• Lwt library function that takes existing i/o channel, username+password, dst host+port and sets up a connection using socks4a / socks5
  • Lwt socks client utility able to use nc-compatible cmd-line, like -X 5 -x localhost:1080 DSTHOST DSTPORT
• A unikernel SOCKS proxy daemon
• Need to find a way to fix the odoc documentation generation so that it can include stuff from Mirage/Lwt when they are built (because they are optional dependencies)