Onsite admin enhancements - split tender

[rechner]

Currently there is no easy method to handle split tender with a partial card and cash payment in the onsite register. There's not really a nice way to express this in the model, since orders are one-to-one with price levels, so a work-around might be to generate a discount code on the fly to cover the cash payment, and record the cash transaction in the order note.

• Any existing applied discount will need to be read and added to cover the transaction, as well.
• Cash button in onsite admin should trigger this split tender type.

[meanderfox]

this is not broken, split tender operations prompt you with an error saying its not supported