title: Set default line style in chart.js
body: <p>Is there any way to set the default line style in chart.js to <code>fill: false</code>? </p>
  
  <p>i.e. in the code below, I shouldn't have to write all the <code>fill: false</code> explicitly.</p>
  
  <pre><code>  type: 'line',
  
    data: {
      labels: data.months,
      datasets: [{
          fill: false,
          label: 'Gross',
          data: data.gross,
          backgroundColor: '#2f7ed8',
          borderColor: '#2f7ed8',
        }, {
          fill: false,
          label: 'Net',
          data: data.net,
          backgroundColor: '#8bbc21',
          borderColor: '#8bbc21',
        },
      ],
    },
  </code></pre>
  
  <p>The documentation says that you can set default options via <code>Chart.defaults.global</code>, but it is not clear to me whether and how you can change things like line style.</p>