[XML-SIG] DTDHandler and EntityResolver

[Lars Marius Garshol]

* Martin v. Loewis
| 
| On 16 Sep, Lars mention that he wants to edit these interfaces into
| xml.sax.xmlreader. Given that we are running short of time: Is that
| really necessary? Adding the interfaces themselves might be ok, but
| having expatreader support them seems not feasible: that would be an
| extension both over Python 2 code freeze, and PyXML 0.6.0.
| 
| Comments?

They are already in xmlreader, except that they are not initialized in
the constructor and that was what I wanted to change.  Only adding the
interfaces is acceptable to me, but it would be better if we could
make pyexpat support them both.

It has the necessary callbacks to do so, and support for DTDHandler is
required for full conformance with the XML 1.0 recommendation (that is
why the handler is there, actually).

DTDHandler is dead simple, EntityResolver more complex.

--Lars M.