WooCommerce PDF Product Vouchers 3.12.4

* Fix - Ensure correct discount calculation when multi-purpose vouchers are redeemed on orders containing subscriptions
* Fix - Correctly apply partially-redeemed vouchers to shopping carts
* Fix - Do not use purchaser name in place of the recipient name if the recipient name is empty
* Fix - When a voucher is on sale, calculate the tax from the regular voucher price so it is correct when redeemed
* Tweak - Limit the product "redeemable by" select field to vouchers that can be redeemed online
* Dev - Fix typo in filter: `wc_pdf_prdouct_vouchers_voucher_search_fields` is now `wc_pdf_product_vouchers_voucher_search_fields`
* Dev - Add missing $email argument to `woocommerce_email_header` and `woocommerce_email_footer`

* Fix - Activate a voided voucher when an order is completed
* Fix - Redeem single-purpose vouchers (SPV) in multiple failed use cases

* Feature - Add QR & Barcodes to vouchers and scan them easily from the admin for quick voucher redemption
* Dev - Namespace the SkyVerge Plugin Framework and move to the /vendor directory
* Localization - Added Italian translation