Clean module layouts and imports.

[hdevalence]

As we flesh out the code, we're placing things in various parts of the module tree and importing various items from various paths, but as things take a clearer form we will have a better idea of the ideal logical structure of the module tree. Before we do any release, we should do a reorganization pass to ensure that the module tree is conceptually coherent, and probably use re-exports to simplify presentation of the external module components to external crates. However, it may not make sense to do this right now, while things are still in flux.

[hdevalence]

Tagged with later because we cannot have encapsulation until more of the parts are in place, and it's useful to be able to drive stuff with the connect stub.

[hdevalence]

Poll::Pending -> Poll::Ready

[hdevalence]

Potential refactorings/cleanups/simplifications:

• remove the Peer prefix on the contents of the peer module (i.e., peer::Client not peer::PeerClient);

• move the initialization functions in peer_set.rs into a submodule and just re-export the init function

[hdevalence]

Going to start working on this, hoping to slip it in before #118...

[hdevalence]

The remaining work for this ticket is to rename structs in the peer_set module.

[dconnolly]

Closed as done (I think???)