Port PIL Handbook tutorial and appendices

[Click here to see the results](http://irskep-pillow.readthedocs.org/en/latest/)

I ported sections 1 (tutorials) and 4 (appendices) from the [PIL Handbook](http://effbot.org/imagingbook/pil-index.htm).

I also switched the docs to use a [Sphinx theme I'm working on](http://sphinx-better-theme.readthedocs.org/en/latest/). Of course I can snip that commit out if you don't like it, but I think you'll like it.

The API reference is now split into "PIL" and "plugins." The latter is larger and less important, so I made it easier to ignore while still just as accessible.

Additionally, I added a `make livehtml` target so you don't have to build/refresh manually while editing.

I skipped the reference and tool sections for now. I (or someone else) can come back and do them later. I just got tired of translating HTML to Sphinx by hand.

Let me know if you want anything changed.