title: How to rotate custom marker in chart.js?
body: <p>I have this problem - I want my chart to have custom markers (points) that rotate depending on the value from the dataset. 
  I have my custom markers (arrows), but I don't know how to rotate them.
  I am using Chart.js</p>
  
  <p>My JS Code:</p>
  
  <pre><code>    var canvas = document.getElementById('myChart');
      var ctx = canvas.getContext('2d');
  
      var yourImage = new Image(30, 30);
      yourImage.src = 'arrow.png';
      var myChart = new Chart(canvas, {
        type: 'scatter',
        data: {
         datasets: [{
          label: 'Scatter Dataset',
          data: [{
              x: 1,
              y: 1.45
              }, {
              x: 2,
              y: 0.25
              }, {
              x: 3,
              y: 2.56
              }, {
              x: 4,
              y: 1.65
             }],
             pointStyle: yourImage,
         }]
      },
      options: {
      scales: {
             xAxes: [{
                 type: 'linear',
                 position: 'bottom'
             }]
            }
         }
      });
  </code></pre>