Add TCP-over-SOCKS proxy support (to enable Mumble over Tor!)

[n8fr8]

I'm a developer with Tor Project and the Guardian Project, and we are really interested in seeing your client support proxy settings with a Force TCP-only mode.

Beyond that a simple "Use with Orbot" (our Tor for Android app) would be great to simplify setup for users (just enable TCP over SOCKS5 to localhost:9050).

We have some code here to show how to use SOCKS5 sockets properly, as well as check if Orbot is installed and running: https://github.com/guardianproject/onionkit

We may end up sending a pull request for this ourselves, but in the meantime, it would be great to have more people out there thinking about proxy support in their apps!