* xpath.c: fixing #61290 "namespace nodes have no parent"
  long standing divergence from the XPath REC. NodeSets
  simply hold a copy of namespace nodes and those node ->next
  points to the parent (which may not be the node carrying the
  definition).
* include/libxml/xpath.h: flagged but didn't added a possible
  speedup
* DOCBparser.c HTMLparser.c: removed some warnings from push
  parser due to new state being added.
* tree.c: new fix from Boris Erdmann
* configure.in c14n.c include/libxml/c14n.h testC14N.c: added
  the XML Canonalization support from Aleksey Sanin
Daniel