e079e82cb1
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.