Allow series->data->marker config obj to overwrite plotOptions->series->marker
Use case: I have a series where I would like only the last point to have a marker. This means that I have to create a marker obj for each point in my series data.
With the change I propose I would only have to create a marker object for the last series data point.
You can apply individual markers: http://jsfiddle.net/highcharts/TtH3V/