Hello,

This is an ergonomy request:

Today, we can navigate from sales shipment lines to the invoices of one line.

I would like to see the following changes:
- if the shipment line is linked to only one invoice: open the invoice directly, not the list
- from the shipment header, allow the user to navigate to the list of all invoice related to the shipment. If the shipment is linked to only one sales invoice (which is the case most of the time): open the invoice directly.

This improvement in navigation could be added everywhere: between sales return and sales credit memo, purchase receipt and purchase invoice, ...