Documentation Documentation Documentation

Here's a first pass at writing some meta-documentation for the documentation system. Documentation.

I'll hold off on merging this until the type stuff actually, you know, works, and open it up for feedback in the meantime. Let me know if there's anything you're unsure about that this doesn't clear up.
This might be a good place to explain a bit of the syntax, in particular, the `doc` in front of the string.

Also, in all of your help strings you might want to include the syntax of the function call, since that is not printed automatically.