Taught doctest about static methods, class methods, and property docstrings
in new-style classes.  As for inspect.py/pydoc.py before it, the new stuff
needed didn't really fit into the old architecture (but was less of a
strain to force-fit here).
New-style class docstrings still aren't found, but that's the subject
of a different bug and I want to fix that right instead of hacking around
it in doctest.