* XPath parser: fixing lexical issues cornercases

* Some complexities in Section 3.7 Lexical Structure of XPath 1.0 spec
  * There used to be some cornercases where function-names could not be used as nodes
  * For example, `node()` is a nodetest, so `/node/` caused an error.
  * In the grammar these include: axisnames,  nodetests, functionnames
  * The NCNames vs functionnames is now impölemented according to the lexical structure section

lib/src/clixon_xpath_parse.h

@@ -44,6 +44,7 @@ struct clixon_xpath_yacc{
     const char           *xpy_name;         /* Name of syntax (for error string) */
     int                   xpy_linenum;      /* Number of \n in parsed buffer */
     const char           *xpy_parse_string; /* original (copy of) parse string */
+    int                   xpy_lex_string_state; /* lex start condition (STRING) */
     void                 *xpy_lexbuf;       /* internal parse buffer from lex */
     xpath_tree           *xpy_top;
 };