Get foodsoft-shop plugin functionality working in main version.

[edgaleano]

Foodsoft-shop as a plugin, see plugins/shop (and also foodcoops/foodsoft#581).

[edgaleano]

we might not need this plugin: from what we understand its just an enhancement on the order page. If we need to improve that view it will be easier to make a new plugin from scratch in the new version.

[wvengen]

This plugin is not strictly necessary. It is just that our users are really used to the interface foodsoft-shop provides (from fresh ordering), since it is like the foodcoop-adam fork in that respect.

[wvengen]

I'd just like to make clear that foodsoft-shop works out of the box with the latest versions of Foodsoft (though needs some configuration to set it up).