Chapter Prose

First draft of the chapter prose, in rst form for now. I'm requesting PR to have someone look at the prose. I've also included an svg diagram, but you'll have to pull the repository to see it. I don't think it's viewable within github...

If you want to pull this, this is the 'chapter' branch from https://github.com/malini/500lines
This might be a good place to put the code inline and walk through the design decisions, rather than referring to them in passing. I might be in the minority but I don't have any experience with the SocketServer module and without referencing the code separately can't really tell what something like TCPThreadingServer does or adds to the SocketServer.