better packaging with setup.py and a few other improvements

Not sure if you were intending to maintain this going forward, but I really like the simplicity of your approach so I started making some improvements.  Apart from a packaging setup, this is also most of the boilerplate you'd need for enabling installation from pypi.  I'm mostly using this for documenting my code without all the overhead of using something like sphinx, so I've also updated poole to include stuff for supporting code highlights with markdown.