message: XPath: Reword brace mismatch errors for clarity
diff: @@ -11272,7 +11272,7 @@ PUGI__NS_BEGIN
  if (!n) return 0;
  if (_lexer.current() != lex_close_brace)
  - return error("Unmatched braces");
  + return error("Expected ')' to match an opening '('");
  _lexer.next();
  @@ -11366,7 +11366,7 @@ PUGI__NS_BEGIN
  if (!n) return 0;
  if (_lexer.current() != lex_close_square_brace)
  - return error("Unmatched square brace");
  + return error("Expected ']' to match an opening '['");
  _lexer.next();
  }
  @@ -11535,7 +11535,7 @@ PUGI__NS_BEGIN
  if (!pred) return 0;
  if (_lexer.current() != lex_close_square_brace)
  - return error("Unmatched square brace");
  + return error("Expected ']' to match an opening '['");
  _lexer.next();
  if (last) last->set_next(pred);
  