This PR adds state name to national borders (`admin_level=2`)
From zoom level 3 there is an added `adm0_l` and `adm0_r` attribute for national borders.
There is 3 main steps:
1) union border lines from OSM and keep separate LineString between intersects
2) create polygons from step 1), create a point in each state polygon, add to this point a state abbreviation from NaturalEarth Data
3) create a short parallel line on the left and right of a small part of the border in 70m distance, and add information about which state overlap this short line.
* Change NE 50m by NE 10m state provinces dataset
* update documentation
Fixes#977
This PR implements the change discussed at #977 to replace Natural Earth 10m states and provinces by the 50m version, since the 10m only covers state borders for US, Canada, Brazil, and Australia.
A few remarks:
* This change only affects zooms 1 to 4, not making any change in borders based in the `OSM Borders` source.
* The `min_zoom<=7` shows the first level regions (level 4 in OSM) as you can check for example for France, Italy, or Spain.
* I don't think it's necessary to simplify the geometries, it would mean adding a new materialized view, or a slower tile generation process.
* This change does not need any change in the styles, even someone could argue it could be interesting to add the country code in this layer as a new field, allowing style editors to filter features by country, but I would prefer to leave that change for another PR.
* Move simplified border tables to OMT as MAT VIEWs
Consolidate derived table creation in OMT repository.
Move all non-original simplified geometry tables from import-osmborder
image to this repo, allowing further optimization.
Later we can remove derived table creation fro mthe import-osmborder image.
Seems like etl and mapping diagrams have been neglected
for a long time. Now it regenerates the files and places
them in the source dir.
This PR also fixes two broken files:
* layers/aerodrome_label/mapping_diagram.png
* layers/housenumber/mapping_diagram.png
They were generated using the newest tools version with the fix
https://github.com/openmaptiles/openmaptiles-tools/pull/65
