ADMIN FIX - REMOVE MANUFACTURER FROM PRODUCT

The problem: Since auto-complete was introduced for Manufacturer's in the Edit Product/Links tab, there has been an issue where if you try to remove the listed manufacturer and save, if you go back in to Edit the product, the manufacturer is still there and hasn't been removed.

It remains and prevents you removing the Manufacturer from Catalog/Manufacturers because it is still linked to a product.

This fix is originally from Qphoria as posted on this thread:
http://forum.opencart.com/viewtopic.php?f=20&t=110198

This is a vQmod version based on the thread to make it really easy to fix without updating core files.
Once installed, simply update your product and when you remove the manufacturer link and save, it will actually be removed.