Avoid the error: Field 'show_warning_vat_required' used in attrs ({'invisible': [('show_warning_vat_required', '=', False)]}) is restricted to the group(s) account.group_account_invoice, sales_team.group_sale_salesman.
A yellow warning banner is now displayed on the partner form view when
the fiscal position requires a VAT number and the VAT number is missing.
This banner replaces the warning message triggered by the onchange.
Improve README of the module with v14 screenshots.
