title: jqPlot aligning zeroes for different y-axes
body: <p>In <code>jqPlot</code>, I have two series rendered in the graph. They show different data, measured in different units, so they each have their own y-axis (<code>yaxis</code> and <code>y2axis</code>).</p>
  
  <p><code>jqPlot</code> constructs both y-axes automatically to suit the range of the data. That is ok - I don't want to set the axis <code>min, max, ticks</code> manually, as the range of the data may vary greatly.</p>
  
  <p>However, I would like to align the <code>0</code> ticks for both <code>y-axes</code> to the same level. Is this possible?</p>
  
  <p><b>Note:</b> One may argue that there is no point to align, for example, <code>0° C</code> temperature with <code>0 ms^-1</code> wind speed, as there is no mathematical relation between the values. But it does look a lot better if it is so, and looking good is the whole point of graphs :)</p>
  
  <p><b>Testing example:</b></p>
  
  <pre><code>var data1 = [[0, 0], [3, 50]];
  var data2 = [[0, 0], [3, -50]];
  
  $.jqplot('chart', [data1, data2], {
    series: [
      { yaxis: 'yaxis' },
      { yaxis: 'y2axis' },
    ]        
  });
  </code></pre>