Add support to Banking module for BuyerGroup to be called from
Cart module. Cart module now supports different price levels for
logged in users, and can display items from the Stock module.
The Stock module now supports updating images for stock items so
that they can also be used by the Cart module. The Browser module
is called from the stock grid, and it now shows upload progress
and image search. Cart sales are also saved to the purchase and
payment modules when items are tracked from the Stock module.