HOTFIX: Setting For Loading Previous Customer Carts For Different Store

Fix for loading previous customer cart that applies to a different store
made this behavior a setting) and made load previous cart not attempt
to load inactive items for the current store.

This new setting is to allow multistores to control the behavior as fits their
circumstance; a multistore that shares catalog across stores will not want
o turn the new setting on necessarily, while multistores that do NOT share
the catalog will want to turn this on, as the popup help explains.

The default behavior is to have the setting off, which is how it functioned
previously to this setting.