WooCommerce PDF Product Vouchers 3.12.4

* Fix - Error in upgrade routine for version 3.1.1

* Tweak - Set voucher type for a template to hint at taxable status
* Tweak - Show tax-inclusive price for voucher value when displaying prices as tax-inclusive in the shop
* Tweak - Adjust redemption behavior based on voucher type for full tax support
* Fix - Ensure order emails show voucher field values, such as recipient name
* Fix - Ensure registered customers see purchased vouchers in the account area

* Tweak - Improve compatibility with some themes/plugins that previously caused issues with PDF generation
* Tweak - Improve security of voucher download URLs
* Tweak - Try to increase PHP time limit, if possible, to avoid Maximum Execution Time Exceeded when generating a voucher PDF
* Fix - Voucher download links in emails did not always work due to nonce protection introduced in 3.0.5