Notification subscriber config section

[Peter Suter]

Trac already has a few notification config options to control default subscriptions:

• always_notify_updater
• always_notify_reporter
• always_notify_owner
• never_notify_self (soon?)

But we don't want always_notify_close_reporter_except_when_reporter_closed_the_ticket. :)

The new INotificationSubscriber makes it easy to add new such rules, but if we provide more implementations we may actually need more config options. Also there could now be different message formats, distribution transports, default subscription priorities (and required authentication and later maybe permissions and more).

We could instead try to add a [notification-subscriber] section:

[notification-subscriber]
always_notify_updater=TicketUpdaterSubscriber
always_notify_updater.default=email, 100, always, text/plain
always_notify_reporter=TicketReportedSubscriber
always_notify_reporter.default=email, 100, always, text/plain
always_notify_owner=TicketOwnerSubscriber
always_notify_owner.default=email, 100, always, text/plain

always_notify_owner.requires_authentication=True
always_notify_owner.permission=CUSTOM_CONFIG_NOTIFY_OWNER_PERMISSION
...

(Or some equivalent notation.)