Test/Verify: remove all variants of a product when product is deleted from database and other code cleanup.

The code of this branch adds SBA table cleanup for products that are deleted through the standard ZC product deletion code.  This will remove all variants that have been populated in the products_with_attributes_stock table for the product(s) being deleted.

Additional code touchups were included to standardize some of the code to ZC available "tools" (use of the TABLE_XXXX constant instead of $DB_PREFIX . "XXXX ...") and some formatting modifications intentional and a few unintentional for code readability.  Have also begun in some cases using the standards proposed in the ZC wiki which include the use of two spaces instead of tabs for code arrangement and readability.