Change to use statemachine:

    States:

	ok
	soft
	soft-urgent
	hard
	ok-again

	soft-urgent is soft, but expiry is < $n$ hours (48?) away.
	All non-ok states revert to ok-again. ok-again turns into
	ok after $n$ hours (168?).

	Notifications are sent on all state transitions except
	ok->ok-again and periodically in the states soft-urgent and
	hard.

	The message text reflects the different states.

	The graph is updated in all states except ok.