added walls and buildings theme

assets/layers/walls_and_buildings/walls_and_buildings.json

@@ -43,5 +43,8 @@
         "render": "2"
       }
     }
+  ],
+  "calculatedTags": [
+    "_entrance=feat.get('entrance')"
   ]
 }

assets/themes/walls_and_buildings/walls_and_buildings.json

@@ -0,0 +1,20 @@
+{
+  "id": "walls_and_buildings",
+  "title": {
+    "en": "Walls and buildings"
+  },
+  "description": {
+    "en": "Buildings are shown with entrance metatags"
+  },
+  "maintainer": "MapComplete",
+  "icon": "./assets/layers/walls_and_buildings/walls_and_buildings.png",
+  "version": "0",
+  "startLat": 50.8465573,
+  "defaultBackgroundId": "CartoDB.Voyager",
+  "startLon": 4.351697,
+  "startZoom": 16,
+  "widenFactor": 2,
+  "layers": [
+    "walls_and_buildings"
+  ]
+}