This PR is solving https://github.com/openmaptiles/openmaptiles/issues/406, partially also https://github.com/openmaptiles/openmaptiles/issues/320.
It is changing source of data for zoomlevel 6 - 8 in `waterway` layer to OSM (relation `waterway = river`), this way it corresponds with `water` layer.
Testing on Europe, z0 - z9 tiles increase size from 20.7 MB to 21.4 MB. We can discuss the level of generalization, but I think this size change is not critical.
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
