Maps: dataLabels placement when the shape loops around the world

[KacperMadej]

Expected behaviour

Placement is to be based on the latitude and longitude corresponding to the center of the region on the map.
Get the lat/long out of the hc-middle-x/hc-middle-y and use that for the dataLabels instead of the current behavior.

Actual behaviour

Placement is based on the bounding box - which doesn't work well for some projections or projection options.

Live demo with steps to reproduce

Asia is wrong in the default demo - https://jsfiddle.net/gh/get/jquery/1.11.0/highslide-software/highcharts.com/tree/master/samples/mapdata/custom/world-continents

After some changes, see Europe, Asia in the wrong places - https://jsfiddle.net/BlackLabel/5w61mt4y/

Product version

Highcharts Maps v9.3+