title: setting per series options when using native array data input format
body: <p>Do the per series options not work unless the input data is in CSV format?</p>
  
  <p>I have the following which attempts to plot a thin line and a thick parabola on the same graph:</p>
  
  <pre><code>g = new Dygraph(document.getElementById('graph'),
    [
      [1,2,1],
      [2,4,4],
      [3,6,9],
      [4,8,16],
      [5,10,25],
      [6,12,36],
      [7,14,49],
      [8,16,64],
      [9,18,81],
      [10,20,100]
    ],
    {
      legend: 'always',
      title: 'Data Chart',
      drawPoints: true,
      labels: ['index', 'doubleX', 'xSquared'],
      series: {
        doubleX: {
          strokeWidth: 0.5
        },
        xSquared: {
          strokeWidth: 2.0
        }
      }
    }
  );
  </code></pre>
  
  <p>But both series just show up with the default display options. I'm not getting any warning messages or anything. Is there a way to get these to work with array input?</p>