Test new documentation infrastructure to replace the wiki pages.

Testing out using sphinx for all regular documentation as well as code
docs.  This uses the Read The Docs theme and the httpdomain sphinx
plugin for REST API documentation.

Requires:
    * pip install sphinx_rtd_theme
    * pip install httpdomain

Build/Test with:
    * ``make`` (default make target is now ``make html``)
    * Open `file://_build/html/index.html`_ in your browser to view.
    * Publish by copying ``docs/_build/html/*`` to the ``gh-pages`` branch.