Since this script isn't normally calling bbs.nodesync() (e.g. to display
any pending inter-node messages/telegrams), we have to check the NODE_INTR
flag manually. Calling bbs.nodesync() directly here to get a more immediate
notice and disconnection message sent to the user.

This check is necessary so that a sysop or the event thread can gracefully
terminate/disconnect a user that's running this script (e.g. when an
exclusive timed event is scheduled to run and thus being prevented to run).
This should help Keyop's reported issue with his weekly msgmaint timed event
having to ungracefully disconnect his user session because he's running this
script.