CreditNotes implementation

[phillipp]

We are going to need CreditNotes (Stornorechnung / Gutschrift) for our business case. The implementation itself is not too complicated, but we should make a decision on the naming scheme and if it is going to be breaking anything or not.

I would propose that we use the Xrechnung::Document as a base class and add a new Xrechnung::Invoice and Xrechnung::CreditNote for the fields that are specific for their respective document types. Other document types (Order etc.) could then be added more easily.

This change would naturally break stuff that uses only Xrechnung::Document so I'd say that would be a good time to release a 1.0 that is more or less complete to use in 95% of business environments.

@corny any thoughts?

[theempij]

Currently developing an german accounting tool in Rails under www.digitalized-accounting.com and some customers are talking about digital invoices. The idea mentioned here sounds good to me although I am not in the gem development.

Credit Note might be the wrong word though. This means more "Gutschrift" than "Storno" I think. But the case should be covered. This issue is quite old. Not sure if this is still relevant.

[phillipp]

@theempij Credit Note is the PEPPOL object name, I don't think it makes much sense to devidate from the european standard here. a Credit Note can be used for both, a Stornorechnung (Korrektur oder Storno einer Rechnung) or a Gutschrift (Rechnung durch den Leistungsempfänger) afaik