Support D3?

Part of the reason I created #1 was I wondered about using this to render `d3`.

I was reading the https://github.com/Olical/react-faux-dom/ source when I saw your Tweet about this project.

I'm not sure exactly what changes are required. I believe some will be small (like `ownerDocument`) or `namespaceURI` while others (like `style` and `querySelector`) will require more time and bytes.

FWIW, here's [their DOM support](https://github.com/Olical/react-faux-dom/blob/master/DOCUMENTATION.md#dom-support) and [their d3 tests](https://github.com/Olical/react-faux-dom/blob/master/test/d3.js). A key first step would be to get `d3.select(document.createElement('div')).append('p').node()` to return to newly created `

It seems like we can either a) add support for this use case into this document b) create another project which imports `undom`. Do you have a preference? Does this use case ([with limitations](https://github.com/Olical/react-faux-dom/pull/30)) seem like a fit for undom "core" or should it be an separate lib?