memory leak: building_type::construction was never released

src/kernel/building.c

@@ -94,6 +94,7 @@ void bt_register(building_type * type)
 
 void free_buildingtype(void *ptr) {
     building_type *btype = (building_type *)ptr;
+    free(btype->construction);
     free(btype->_name);
     free(btype);
 }