Added for 9530651

Because we don't have sane recurring reminders just yet, we need to handle them in the UI in a rather bizarre way.  Also, we can't unit test this stuff because EKEventStore is only really unit testable inside the EventKit project.

This is how the backend works right now.
- A recurring reminder starts out as just one reminder in the database.
- When you check it off, it gets cloned to a completed version of itself with a different UUID, and its dates are updated to those of the next recurrence.  So now there are two reminders.
- If you uncheck an old clone, it becomes incomplete, so you may have more than one incomplete version of a reminder.
- There is no way to tell from the db whether reminders came from the same recurring reminder.  For this bug, we'll introduce a hack in EventKit that lets us know the parent UUID of reminders completed in our event store, but that won't be persistent data.

#1
- Show a recurring reminder
- Check it.  It should stay checked.
- Swipe to another list and come back
- Now there should be a new reminder in its place

#2
- Show a recurring reminder
- Check it.
- Uncheck it.  There should still be just one reminder in the list.
- Swipe to another list and come back.
- Unfortunately, now we need to show both reminders, so that search works properly.

#3
- Show a recurring reminder in Due mode
- Check it
- Go to List mode and find the new occurrence of that reminder
- Check it.  At this point, only the last completed occurrence should show up, not the one we completed in Due mode.

#4
- Show a recurring reminder
- Check it (due to the way we save things after a delay, you may have to wait a little after this step)
- Uncheck it.  You should only see one occurrence
- Swipe away and back.  You should see two occurrences
- Check the earlier occurrence.  You should still see two occurrences.

#5
- Show a recurring reminder
- Check it (due to the way we save things after a delay, you may have to wait a little after this step)
- Uncheck it.  You should only see one occurrence
- Swipe away and back.  You should see two occurrences
- Check the later occurrence.  You should still see two occurrences.