Quote, order and invoice Dates are weird

Hi there!

I found some inconsistent behavior of the dates of quotes, orders and invoices.

Orders - in my opinion - do have the right behavior. Theres an "order date" you can change which is used as date on the actual order.

Invoices do also have an "invoice date" but that isn't used to display the date on the invoice. The creation date - found in the tab order history - is displayed. But there's a due date calculated as "invoice date" plus "credit period".

When it comes to quotes it's even getting more complicated. There's a "valid until" date which is not used as such but as the displayed date of the quote. In addition to that I think it would make sense to have this function consitent with invoices. Having a "quote date" and a "validity period".

greetings Moritz