Multiple Socks Server support in Tor Client
This feature is the Tor client support of the feature described on https://trac.torproject.org/projects/tor/ticket/6287 .
The Tor client should support the configuration of multiple Socks and Proxy server and handle the logic to try connection using each of them until one is found to work.
An improvement related to the multiple socks client is also available on https://trac.torproject.org/projects/tor/ticket/6288 .