YITH WooCommerce PDF Invoice 4.16.0

Fix: VAT number and SSN number not properly retrieved from the customer details.

Fix: Gift cards row shown in invoice even if no gift cards were used.
Dev: filter 'yith_pdf_invoice_after_customer_content' in customer-details.php template.

• New: show gift card amount on invoices.
• Dev: filter 'yith_pdf_invoice_show_gift_card_amount' lets third party plugin to change the layout for 'gift card discount' row in invoices.