Woocommerce Software Add-on 1.9.2

* Feature - Added compatibility with WooCommerce High-Performance Order Storage.
* Tweak - Added links to the license keys, the reports, the documentation page, and to get support in the plugin list.
* Tweak - Updated plugin author.
* Tweak - Tested compatibility up to WC 7.3
* Tweak - Tested compatibility with WP 6.1
* Fix - Fixed broken 'Total software sales' and 'Total software sold' metrics in reports.
* Dev - Implement the singleton pattern in the main plugin class.
* Dev - Updated the minimum requirements to WC 3.5, WP 4.7, and PHP 5.4

* Fix - Replaced deprecated jQuery 3 methods.
* Tweak - WC 5.2.2 compatibility.
* Tweak - WP 5.7.1 compatibility.

* Fix - Fix: Prevent critical errors by passing the correct number of args to woocommerce_email_header/footer in email templates.
* Tweak - WC 4.9 compatibility.
* Tweak - WP 5.6 compatibility.