Module overview interlinking

Presently we're including a summary for modules at the top of their page. These summaries include classes, methods, and show their inheritance/membership. For instance...

https://stem.readthedocs.org/en/latest/api/control.html

This is fine and well, but I'm doing it via a preformatted text block to take advantage of the monospaced text to show membership. This is a hack, and doing it this way means that we can't include links to the class/method documentation.

We should check to see if there's a better way of doing module overviews, maybe asking on the sphinx list.