but puts the changelog in a more data driven format, so that we
can begin linking version directives with them as well
as with migration documents, once those are also moved into sphinx.

- build a new Sphinx extension that allows dialect info
to be entered as directives which is then rendered consistently
throughout all dialect/dbapi sections
- break out the "empty_strings" requirement for oracle test

- Documentation has been converted to Sphinx.
In particular, the generated API documentation
has been constructed into a full blown
"API Reference" section which organizes
editorial documentation combined with
generated docstrings.   Cross linking between
sections and API docs are vastly improved,
a javascript-powered search feature is
provided, and a full index of all
classes, functions and members is provided.