This PR creates larger polygons of `residential` land-use areas for upper zoom levels (especially for zoom 6 - 10).
Clusters are created with the same logic as for [`building on z13`](b14da2eafb/layers/building/update_building.sql (L34-L49)).
The generalization of land-use prolongs the `import-sql` step of the `landuse` layer. But it is still faster than the `building z13` generalization which with the parallel importing keeps the whole `import-sql` time untouched.
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
