[ENH] Initial effort in py3k support

I have a project that has labeled arrays intertwined throughout it.  I have an interest in getting my project up to speed with py3k, and so I thought I would take a stab at getting larry up to it as well.  This PR is incomplete, as there are many test failures, but it is a good first step.

I should also note that this is my first major foray into py3k, so I really am just stabbing in the dark here.