RFC: example configure hook

[yschimke]

Key line is really just

configure(address.socketFactory(), new Socket(proxy));

Question is whether OkHttp should support a configure hook for creating raw sockets, that is hit in all cases?

Currently a SocketFactory can be used to configure the socket created, except for when a SOCKS proxy is used.

    rawSocket = proxy.type() == Proxy.Type.DIRECT || proxy.type() == Proxy.Type.HTTP
        ? address.socketFactory().createSocket()
        : new Socket(proxy);

Configure hook options?

1. poor OptionalMethod like below.
2. an optional interface for SocketFactory supporting just a configureSocket method?

[yschimke]

relates to #3537

[yschimke]

Closing for now as it's not affecting me and SOCKS is a pretty obscure case