a new specific type for XSLT:
- xpathInternals.h xpath.[ch] debugXML.c: added the XPATH_XSLT_TREE
  type correponding to an XSLT result tree fragment. Share most
  of the data format with node set, as well as operators.
- HTMLtree.c: added a newline at the end of the doctype output
  whe this one is not present initially.
- tree.c: make sure taht the parent and doc pointers are properly
  set when copying attributes (lists).
Daniel