[XML-SIG] SAX API clarifications

[Lars Marius Garshol]

* Fred L. Drake, Jr.
| 
| I've made clarifications in the SAX documentation.  

Very good. This solves part of the problem.

| If anything further is needed, please file a bug report in the
| Python project at SourceForge: [...]

I would, if SourceForge would only work. The web interface seems
totally dead.

We also need to change this, in xmlsaxhandler.tex, so that the default
becomes 'false'.

\begin{datadesc}{feature_namespaces}
  Value: \code{"http://xml.org/sax/features/namespaces"}\\
  true: Perform Namespace processing (default).\\
  false: Optionally do not perform Namespace processing
         (implies namespace-prefixes).\\
  access: (parsing) read-only; (not parsing) read/write
\end{datadesc}

--Lars M.