This section describes the concept of payment methods.
You can add as many payment methods as you want.
All valid payment methods are displayed for selection to the shop customer. A payment method is valid if all criteria of the payment method are true.
Payment methods can have many prices which are, as the payment method itself,
also dependent of criteria. The first price which is valid - all of its criteria
are true - is the current price for the payment method. If no price is valid the
default price is taken (from the