Improve country geographic data

[miridius]

Goals:

• [ ] Improve resolution for small/island nations
• [ ] Make sure data is as accurate/official as possible, try to avoid arguments about conflict zones
• [ ] Expand to include territories/dependencies
• [ ] Figure out if we should exclude some countries from daily challenges (and if so which ones), e.g. anything with too small an area or the ones that are super obvious like USA.

A page linked in the leaflet FAQ recommended this as a good source of such data: https://www.naturalearthdata.com/

[miridius]

GeoJSON versions of Natural Earth data are available inside their git repo: https://github.com/nvkelso/natural-earth-vector/tree/master/geojson

Only issue is it's all in one file and is huge (13Mb) so we'd want to split it out into each country for serving to the web client probably

[miridius]

Some notes after playing around a little

• The GeoJSON files in the Natural Earth git repo are not full resolution, they have a lot fewer points than the raw shapefile data that can be downloaded from https://www.naturalearthdata.com/
• That's fine because it's quite easy to convert shapefile data to GeoJSON or TopoJSON using https://mapshaper.org/
• We would have to split the file up into individual countries as it's too large otherwise but that's pretty easy to do, it's just JSON.
• However there are still a few issues to solve:
  1. Natural Earth use a different map projection (Equirectangular projection, EPSG:4326), which is supported by Leaflet but is not supported by the open street map tile servers I tried. So we either need a different tile server or to convert the projection
  2. Natural Earth show de facto borders rather than de jure, meaning areas of conflict are shown by whoever controls them currently on the ground. This means that Ukraine is shown without Crimea, and Palestine isn't shown at all and is instead part of Israel, for example. They do however also have a set of data for regions of conflict which could then be overlayed... or prebuilt versions of the map from the point of view of different nations... unfortunately there's no easy answer for what's the right path here I think
  3. We need to decide how to define a "country"... there's so many options for how to handle things like territories and so on. For the sake of making it easier to display on the map, it might be worth separating territories away from their parent countries.