List Flag: notify-renew

Causes listmanager to notify owners via e-mail when any subscriber is
notified about either:

(a) the fact that her/his subscription is about to expire, and she/he should
    use the "renew" command to renew the subscription; or
(b) the fact that her/his subscription is being terminated due to non-response
    to such a notice

See also: renewcount renewfreq
