WooCommerce Product Add-Ons 7.2.0

* Fix - Important: Security improvements.
* New - Added admin notice to stores that use a PHP version earlier than 7.0.
* Tweak - Added a notice when addons cannot be saved due to a low 'max_input_vars' value.
* Tweak - Updated the logic that determines in which admin screens, Product Add-Ons styles/scripts are loaded.
* Tweak - Optimized the way global addons are saved.
* Fix - Fixed a fatal error triggered when dividing the addon price by a zero quantity.

* New - Important: Bumped minimum required versions.
* Fix - Important: Security improvements.
* Fix - Fixed an issue that prevented long text addons from being validated.

* Fix - Fixed an issue that prevented addons totals from showing up if required Addons were selected before variations.
* Tweak - Introduced basic telemetry to collect data on extension usage when tracking is enabled.