minetest.get_server_status()
minetest.request_shutdown()
EnvRef:clear_objects()

Add after_destruct and cache the existence of on_construct, on_destruct and after_destruct for quick skipping when a node does not have them

Add ObjRef:is_player() and modify ObjRef:get_player_name() to always return a string to aid better inter-object compatibility of code that assumes objects to be players