Have a way to create an unbootstrapped client?

We might want to create a client without having bootstrapped it. It might be a client that's in the progress of bootstrapping, or it might be a client that hasn't started bootstrapping yet.

These might be separate types than the main TorClient type, if they expose different functionality.

If a client is in the process of bootstrapping, we should expose bootstrapping information from it (see #96 (closed)).

Something like this ticket may be needed for #278 (closed).