First draft of proposal

`proposal.tex` is a first cut at the main body of the proposal.  Search for 'fixme' in the text to find specific to-do items:

* Paul Wilson/Katy Huff: please describe The Hacker Within.
* Ethan White: please give us a couple of paragraphs on career management for our part-time grad student helpers.
* Tracy Teal: please give us a couple of paragraphs on data management.

And everyone: please comment on the PR.