calculates the font size on each li element
according to their data-weight attribut
function addListElementFontSize(element)
    {
      var hDataWeight = -9007199254740992;
      var lDataWeight = 9007199254740992;
      $.each(element.find("li"), function(){
        cDataWeight = getDataWeight(this);
        if (cDataWeight == undefined)
        {
          logWarning("No \"data-weight\" attribut defined on <li> element");
        }
        else
        {
          hDataWeight = cDataWeight > hDataWeight ? cDataWeight : hDataWeight;
          lDataWeight = cDataWeight < lDataWeight ? cDataWeight : lDataWeight;
        }
      });
      $.each(element.find("li"), function(){
        var dataWeight = getDataWeight(this);
        var percent = Math.abs((dataWeight - lDataWeight)/(lDataWeight - hDataWeight));
        $(this).css('font-size', (1 + (percent * settings['multiplier'])) + "em");
      });

    }