Can't edit nodes created with the count parameter

Issue Summary

If you create a repeating event using the count parameter to limit the number of repeats, it will give you an error when you try to edit the nodes. The reason this was originally put in back in the initial version is that trying to do the math when editing gets messy. As time progresses, trying to determine how many counts are left and how many have gone by could get complicated.

The two options I see:
1. Calculate the end date based on the count, and use that when editing. This might mean hiding the count param.
2. Bite the bullet and do the math.