Make shop more modular

[bummzack]

There are several components in the core that don't really belong to a "core". The problem is, that it's currently really hard to find anybody that maintains modules, but to improve overall quality of shop, I suggest to strip down the codebase by quite a bit.

The following features could be moved to separate modules:

• Dashboard support (currently core contains some classes that build upon the dashboard module)
• Shop-Reports
• OpenGraph support (core contains some methods to work with the opengraph module). These aren't in a good state though
• Variations (these were explicitly built with modularity in mind, but yet they are still in core)
• Zones & Zones Modeladmin (I can't find any place where this is being used in core. Should probably be part of the shipping module?)

Did I miss anything? Opinions?

[wilr]

@bummzack Variations, Open Graph, Dashboard makes a large amount of sense. Still a few modifers lying around for shipping in core - I'd imagine these should all be brought out to the shipping module as well.

[wernerkrauss]

Also e.g. an OrderItem should have the possibility to define its EditForm.

I built a CustomProductType where you can register for something (e.g. the Name and Address is bound to that CustomOrderItem), how can I easily add functionality to correct a typo in your name?

Same would be if we have a GiftCardItem where you can set a Price or some other special parameters.