Be sure to clear any existing exceptions.

Fixes mysteriously appearing exceptions when creating an
event after editing/removing an existing event with exceptions and
both events have overlapping recurrence dates.

js/kronolith.js

@@ -5664,6 +5664,7 @@ KronolithCore = {
         $('kronolithEventTarget').show();
         $('kronolithEventTargetRO').hide();
         $('kronolithEventForm').down('.kronolithFormActions .kronolithSeparator').show();
+        $('kronolithEventExceptions').clear();
         if (id) {
             // An id passed to this function indicates we are editing an event.
             RedBox.loading();