XPath without a XPath syntax error
item_xmlfunc.cc:
  Error message didn't happen because after
  a failing attempt to parse RelativeLocationPath,
  my_xpath_parse_AbsoluteLocationPath() returned success.
  Changeing logic a bit:
  - Try to parse EOF first, return success if true.
  - Then try to parse RelativeLocationPath(), return success if true.
  - Otherwise return failure.
xml.result:
  Adding test case.
  Also, this change made it possible to generate 
  an error message earlier in the case of another
  bad XPATH syntax.
xml.test:
  Adding test case.