2 - should transforms for a given stylesheet be thread clean,
3 or can a stylesheet be enriched with document specific
4 informations and cleaned up later ?
8 -> provide functions to circulate in the import tree of stylesheets
11 -> try to optimize for ID scan and tests.
14 -> add error checks on all returns
19 -> macros, config, verbosity ?
21 Support for disable-output-escaping="yes":
22 -> looks problematic, libxml has no support for anything like this,
23 and unless adding a new node type :-( or tweaking text node and
24 output routines this is gonna be messy ... must be handled at libxml
28 -> check the version stuff, design a separate module for error interfacing
29 and default handling, parsing vs. runtime, fatal / compat / warning,
30 and lack of optionnal features.