[IMP] account_invoice_update_wizard : Adapt wizard view and button to make it usable on accountring entries + small improvements

[florian-dacosta]

The goal is mainly to update an analytic account on a accountring entry.

Use case : Set a default analytic account on automatic entries like currency rate exchange. Use this module to be able to change the analytic account depending on your real need. (this currency rate exchange entry is not even allowed to be set to draft)

Also :

• Rename bill reference to invoice bill reference, to have a consitent name in wizard with the name of the field on invoice
• Add possibility to change invoice date (only for supplier invoices/refunds)

@alexis-via