0e17d53f42
Unblocks ZeLonewolf/openstreetmap-americana#51 Currently, OpenMapTiles renders protected areas at zoom 6 and higher. However, the western United States has protected areas that are so vast that it makes sense to render these areas as low as zoom 4, as noted in ZeLonewolf/openstreetmap-americana#51 This PR extends the generalization of park features from its current termination at zoom 6 to zoom 4. Here is an example from the Americana style of rendering protected areas at zoom 6, which is currently the lowest supported zoom: https://zelonewolf.github.io/openstreetmap-americana/#6/45.313/-111.721 We would like to provide rendering at zoom 4 (no labels) and zoom 5 (with labels) in the Americana style. Below are samples generated from this PR for Idaho, USA: Zoom 4:  Zoom 5: 
