xml.result, xml.test:
  Adding test case.
item_xmlfunc.cc:
  Fixed that the "!" character written at the end was ignored.

  Now if we try to scan "!=", and if "!" is not
  followed by "=", we rollback lex scanner back 
  to "!" token, so the parser will start to check
  the next rule from the "!" character again.

  Previously parser started from the next character,
  which was EOF in the example in xml.test,
  which led to query being successfully parsed,
  instead of producing a syntax error.