Make is possible to render & replace nodes

[zpao]

This has come up a bunch, it might be time to just do it.

[nathansobo]

I'm experimenting with using React to render our editor views in Atom. We're trying to make Atom as agnostic as possible when it comes to view frameworks, and I'm shooting for a simple standard in which views assume that other views expose an .element property which is the top-level DOM element for that view.

I could be missing important details here, but it would be great to be able to create a detached component instance and just request its root element, then attach that element wherever. Then a React component would look pretty much like any other view from the perspective of the rest of the system. It would just be an object with an .element property.

[sophiebits]

Might make sense to wait to do this until after @sebmarkbage's inverted-control stuff.

[sophiebits]

Closing in favor of #1711 which solves this problem and actually has a concrete API proposal attached.