Improve label position

[mtennekes]

Method:

• calculate centroids for each zone, using directions and distances
• if centroid is inside polygon, use it, otherwise use any point in polygon (which may happen after intersection with area.

[Robinlovelace]

Good thinking Martijn, are you up for giving it a go?

[mtennekes]

Yes, but it will be after the summer holidays. Hopefully before the conference.

This may be useful: https://twitter.com/edzerpebesma/status/1357372616126959621