Setup and reference

Reference docs

and fix a ReST issue.

Also the details aren't important here, so moved to a footnote.

Still need to discuss zconfig

Writing persistent objects

See http://stackoverflow.com/questions/9153473/sphinx-values-for-attributes-reported-as-none/39276413

Merge branch 'writing-persistent-objects' of github.com:zopefoundation/zodbdocs into writing-persistent-objects

Still more work to do.

Added machinery to make the documentation testable.

Still more work to do.

Added machinery to make the documentation testable.

Demote old guide