* doc/examples/*: added io1.c an example ox xmlIO usage and io1.res
  test result, fixed a awful lot of memory leaks showing up in
  testWriter.c, changed the examples and the Makefiles to test
  memory leaks.
* xmlwriter.c: fixed a memory leak
* Makefile.am: run the doc/examples regression tests as part of
  make tests
* xpath.c include/libxml/xpath.h: added xmlXPathCtxtCompile() to
  compile an XPath expression within a context, currently the goal
  is to be able to reuse the XSLT stylesheet dictionnary, but this
  opens the door to others possible optimizations.
* dict.c include/libxml/dict.h: added xmlDictCreateSub() which allows
  to build a new dictionnary based on another read-only dictionnary.
  This is needed for XSLT to keep the stylesheet dictionnary read-only
  while being able to reuse the strings for the transformation
  dictionnary.
* xinclude.c: fixed a dictionnar reference counting problem occuring
  when document parsing failed.
* testSAX.c: adding option --repeat for timing 100times the parsing
* doc/* : rebuilt all the docs
Daniel