Render Dam and Dykes

[Florimondable]

Example https://www.cyclosm.org/#map=17/49.74473/3.79254/cyclosm

[Florimondable]

Not sure dykes is very necessary, and there is the area and the linear feature to manage.
May be it should be render with embankment and cutting.

[Phyks]

Dams are now rendered. Not sure of the interest of having dykes rendered, plus regular osm.org style does not render them either gravitystorm/openstreetmap-carto#823. We can probably close this one, isn't it?