Missing override for retina icon setting in leaflet.drupal.js

I'm really sorry but I haven't got time right now to provide a patch, but there is a missing override for a leaflet marker icon which allows a retina image to be defined. Here is a quick bit of code which when added to line 288 of leaflet.drupal.js allows a retina image to be used:

if (marker.icon.iconRetinaUrl) {
  icon.options.iconRetinaUrl = marker.icon.iconRetinaUrl;
}

This would then be used in your custom $points as:

 $points[0]['icon']['iconUrl'] = 'my_custom_path/marker-icon.png';
 $points[0]['icon']['iconRetinaUrl'] =  'my_custom_path/marker-icon-2x.png';