KeepAlive (or custom Agent)

[julienschmidt]

For many use-cases it would be favorable if we could convince Twit to use keepAlive i.e. keep connections open instead of opening a new connection for every request.

request ships with forever-agent for that reason. It would be great if one could active forever-agent or even use a custom Agent somehow.
It might even make sense to use such an Agent per default.