- Pxp_document: Add hooks that can be set by the user for:
This would be useful for automatically maintaining an index
of elements (by name), if this is required.
- Pxp_dtd: Add class type for dtd
- Finish pxp_xpath. Add support in preprocessor for XPath expressions.
The functor should get a set of nodes as argument, so one can experiment
with various set implementations.