Improvements and fixes

Plant alarms now arrive on a phone as push notifications.

• Plant alarms now arrive on a phone as push notifications, including on a device registered while a notification is still unread.
• An "Open events" column can now be switched on in the inverter, combiner box and string tables, and an event opened from the row.
• In a plant's analysis, a combiner box or string now shows red while its parent inverter has an open outage.
• A string that stops producing now raises a normal-priority notification instead of a high-priority one, while events already open keep their priority.