private static boolean nameChar(int codepoint, boolean first) {
        // NameChar ::= NameStartChar | "-" | "." | [0-9] | #xB7 | [#x0300-#x036F] | [#x203F-#x2040]
        boolean valid = nameStartSet(codepoint);
        return first ? valid : valid || nameSetExceptStart(codepoint);
    }
Returns the path to the given xml node, where each node name is separated by the given separator string.

@param n the xml node to find path to
@param sep the separator string
@return the path to the xml node as a String
vespajlib/src/main/java/com/yahoo/text/XML.java