[XML-SIG] Uniform interface with Python 2.0

[Lars Marius Garshol]

* Fred L. Drake, Jr.
| 
| Bug fixes can just get checked in.  Large changes should probably go
| through the patch manager, allowing us to review and record our
| comments.

OK.  It's all in the patch manager now, as:

  101570         *NS methods on handler.py
  101571         adds make_parser to xml.sax
  101572         updates XMLGenerator to new interfaces
  101573         a first start on updating expatreader.py

More remains to be added, mainly to expatreader.py, and there is also
the issue of the InputSource and EntityResolver classes.

--Lars M.