Remove charged products from patient history when reversing invoices

From http://www.openvpms.org/forum/product-updates-invoice-reversal-bugenhancement

We recently ran into an issue where one of our vets logged a euthanasia against a client incorrectly. One doctor had thought that it was a probable euthanasia, and so created an invoice with a euth on it. A different doctor then carried on with that invoice and ended up finalising it. We have an update on the euthanasia product to mark the patient deceased.

The problem we're having is that we can't delete the euthanasia from the medical record. We tried reversing the invoice (with a credit), but that had no effect.

This should be changed so that when reversing invoices:

• any invoice item being reversed is removed from the patient history

• any medication linked to the invoice item being reversed is removed from the patient history

The invoice item and medication acts will still be linked to the original invoice.

The following items from the original invoice will be retained:

• Investigations

• Reminders

Note that creating a Credit for a medication will not remove any existing medication - it must be done by invoice reversal.