Add layer housenumber

layers/housenumber/layer.sql

@@ -0,0 +1,5 @@
+CREATE OR REPLACE FUNCTION layer_housenumber(bbox geometry, zoom_level integer)
+RETURNS TABLE(osm_id bigint, geometry geometry, housenumber text) AS $$
+    SELECT osm_id, geometry, housenumber FROM osm_housenumber_point
+    WHERE zoom_level >= 14 AND geometry && bbox;
+$$ LANGUAGE SQL IMMUTABLE;