Select parents automatically

The functionality on "Select parents automatically" does not work if JQUERT > 1.6
need to change .attr to .prop:

current:

      if(checkbox.attr('checked')) {
        checkbox.parents('ul.term-reference-tree-level li').children('div.form-item').children('input[type=checkbox]').each(function() {
          $(this).attr('checked', checkbox.attr('checked'));

should be:

     if(checkbox.prop('checked')) {
        checkbox.parents('ul.term-reference-tree-level li').children('div.form-item').children('input[type=checkbox]').each(function() {
             $(this).prop('checked', checkbox.prop('checked'));

see http://forum.jquery.com/topic/please-explain-attr-vs-prop-change-in-1-6