Change history for date fields in CRM order

The change history for dates has different logic then other fields.

The feather of date's change history are as below:

1. If user deletes a date, the date value deleted is not recorded into the change history. It displays blank in both old and new value fields in the change history.
2. If user changes a date, the change history will have the information about the changed date values, the new value and old value are both filled.