title: Include custom markers in export
body: <p>I'm trying to export an AmMap with custom markers on it. This example show some custom markers, try exporting the map and you'll find that it has no markers at all in the image: <a href="https://codepen.io/anon/pen/gwNevz" rel="nofollow">https://codepen.io/anon/pen/gwNevz</a></p>
  
  <p>The main method of adding the custom markers is to add it as a separate DOM child:</p>
  
  <pre><code>image.chart.chartDiv.appendChild( holder );
  </code></pre>
  
  <p>This is essentially the AmCharts example (<a href="https://www.amcharts.com/demos/custom-html-elements-map-markers/" rel="nofollow">https://www.amcharts.com/demos/custom-html-elements-map-markers/</a>) but with exporting enabled</p>
  
  <p>The standard export plugin omit the custom markers. I tried adding the custom markers to other divs, but it did not matter. I also tried AmMaps-independent approaches (eg html2canvas) but those were unsuccessful so far.</p>
  
  <p>Any ideas how to do this?</p>