Add map polygons for existing skycultures

[gzotti]

Is your feature request related to a problem? Please describe.
V26.1 introduces map polygons for skycultures. While the SCM plugin can be used to draw them in new SCs, we need about 50 definitions for the existing SCs.

Describe the solution you'd like
GeoJSON files should be added.

Describe alternatives you've considered
So far the map info is missing, making the SC map selector less useful.

Additional context
The GeoJSON can also be defined and edited with GIS programs like QGIS. A QGIS plugin may also help in the process.

[github-actions]

Hello @gzotti!

Thank you for suggesting this enhancement.

[alex-w]

The link to specification of GeoJSON is welcome into User Guide

[gzotti]

Sure, this still has to go in the SUG 26.1. But SUG finalizes between RC3 and release, now I still test and improve (language, instructions, ...) after SCM merge.