WooCommerce Account Funds 3.1.1

* Fix - The 'Account funds' checkbox didn't work on the cart page when modifying the cart at the same time.

* Feature - Added support for "Refunds" to the "Account Funds" payment gateway.
* Tweak - Funds are restored after canceling or refunding an order.
* Tweak - Don't set the Order total to zero when the payment gateway is "Account Funds".
* Tweak - Display the "Funds used" row in the Order details before the "Payment gateway" row.
* Tweak - Hide the "Funds used" row in the Order details when the payment gateway is "Account Funds".
* Tweak - Tested compatibility up to WC 5.2.
* Fix - Unlock the used funds when canceling the PayPal payment process.
* Fix - Fixed warnings thrown for using the deprecated method `WC_Order->get_product_from_item()`.
* Dev - Updated the minimum requirements to WC 3.2 and WP 4.4.

* Tweak - Always display the 'Account funds' payment gateway when there are enough funds to pay the Order.
* Tweak - Hide the 'Account funds' checkbox field when the payment gateway is available.
* Tweak - The Order total is not set to zero when selecting the 'Account funds' as the payment gateway during checkout.