Version 0.16
------------
Add ``.unflatten()`` method to ``Graph``, ``Digraph``, and ``Source``. Add
standalone ``unflatten()``.
Make ``Source.__str__()`` return the ``.source`` instead of the ``repr()``
(like ``Graph`` and ``Digraph``).
Render with ``dot -K<engine> ...`` instead of ``<engine> ...`` internally
(work around `upstream issue
Add documentation hint to archived upstream version for Windows.
Re-render most documentation graphs with Graphviz 2.44.1.
6e8b51e647