WooCommerce Checkout Add-Ons 2.7.3

* Fix - Ensure textarea and file add-on values are displayed correctly on Thank You and View Order pages

* Fix - Ensure add-on values can be correctly saved at checkout when using a locale in WordPress other than English
* Misc - Add support for WooCommerce 3.9
* Localization - Update Italian translation

* Tweak - Add support for Customer/Order/Coupon Export v5 XML exports