v2.3

• plans: some enhancements (#2482)
• apps/notifications: add notification for moderator feedback (#2492)
• apps/notifications: do not notify followers on new comments or ideas (#2523)
• apps/offlineevents: Send notification emails for upcoming events (#2527)
• apps/notifications: Make notification times configurable (liqd/adhocracy4#395)
• lots of fixes, cleanups, dependency updates