Admin to store-front extension for each pages.

Now that most features has been fixed in Opencart v2.1.0.1, it would be great to have an extension feature for each pages from the admin that involves manipulating the store-front end. In Opencart 1.5x releases, we use to have the layout module page for several pages under the admin which has been moved to the modules, which is fine.

However, rather than removing the old layout module feature, it could rather be replaced with the extension page for every page affecting the store-front end such as: Categories, Products, Cart, etc ...

This methodology would only require an extra route to be used or by originally using the controller from the loader within the engine as it would not impact the original routes that has been programmed in the first place out of the box.

For instance, the category and product extensions could be uploaded under the admin/controller/extension/catalog folder and catalog/controller/extension/catalog folder, followed each by the language, model and template files, rather than using the modification folder in the system folder, which each distributions affects the same file on anyhow compared to the extensions.

As for the admin orders, it would be great to establish layouts the same way the admin module layouts currently works in order to establish separated API order tasks so that each routes wouldn't require integration within the already existing order_x.tpl files.

That could be done as a module, other than that it involves further core changes or it would be just a "temporary" solution