Order info should show & use checkout steps
Require interface whenever possible
CS
Implemented checkout step url generator in frontend module
CS
Fixed outdated calls to IsotopeFrontend class
Use static method System::log
Use static method Controller::redirect
Removed cart template selection, added collection template selection
Removed support to generate PDF in product collection
Removed iso_invoice template. The product collection does not know a default template
Overriding global configuration is not the job of a model
ProductCollection::generate does not render an invoice but just a collection of products
Overriding global configuration is not the job of a model
Use "false" instead of "null" for uninitialized value
ProductCollection can render iso_collection_ templates
OrderProducts checkout step uses collection to render products
Frontend class now handles "collection to template"
Removed old cart templates and other outdated templates
Must use uncached access to collection items

If cache is enabled, the old values would be retrieved after
updating an item (e.g. updating quantity)