[XML-SIG] Simple DOM API a la dom4j/jdom

[Rich Salz]

> It'd be neat if an XpDom node had methods to:
>    * get all matching nodes
>    * get the next matching node

Those are fairly easy with Python generators.  Every once in a while 
someone suggest a more python XML document interface (PyDOM is bad; how 
about PyXDI? :).  Certainly leveraging generators and making iterators 
should be a key part.

It would be interesting to restructure XPath to be generator based. 
That'd break compatibility with most python releases, of course.
	/r$