- xpath.[ch]: still a lot of cleanup based on XSLT, added
  xmlXPathConvert{String,Number,Boolean} to be able to make
  type casts without a context stack, fixed some implementation
  problems related to the absence of context at parse-time,
  added xmlXPathEvalPredicate() and xmlXPathFreeCompExpr()
  in the public API too
- xpointer.c xpathInternals.h: we need to know at parse time
  whether we are compiling an XPointer
Daniel