Refactor place layer

layers/place/types.sql

@@ -0,0 +1,7 @@
+DO $$
+BEGIN
+    IF NOT EXISTS (SELECT 1 FROM pg_type WHERE typname = 'place_subclass') THEN
+		CREATE TYPE place_subclass AS ENUM ('city', 'town', 'village', 'hamlet', 'suburb', 'neighbourhood', 'isolated_dwelling');
+    END IF;
+END
+$$;