Tune email notifs to make them quieter:

 * After initial 10 minute window, only alert every 24h for room notifs
 * Reset room state after 6h of idleness
 * Synchronise throttles for messages sent in the same notif, so the 24 hourly notifs 'line up'
 * Fix the email subjects to say what triggered the notification
 * Order the rooms in reverse activity order in the email, so the 'reason' room should always come first