WooCommerce Composite Products 10.4.0

* Important - Added support for WooCommerce 3.7+.
* Important - PHP 5.6.20+ is now required.
* Tweak - Ignore 'woocommerce_before_cart_item_quantity_zero' action under WC 3.7+.
* Fix - Prevent Summary Widget from erroring when attempting to call widget() in a non-Composite type product page.

* Fix - Selection details fail to load when 'Product Add-Ons' visibility option is disabled at component level from the 'Advanced Settings' section.
* Fix - Components with pre-selected variable products incorrectly pass validation on initialization.
* Fix - REST API container line item field props do not persist when creating a new order that contains configured Composites.
* Fix - REST API fatal error when attempting to add an invalid Composite configuration to an order.

* Important - Removed deprecated and unused WC_CP_API class.
* Fix - Zero prices displayed next to Component Options when 'Priced Individually' is disabled but 'Option Prices' was previously saved as 'Relative'.
* Fix - Round component subtotals when calculating container item subtotal in order templates.
* Fix - Help tips not displaying in Scenarios.
* Fix - Update component option backorder string.
* Fix - Selection in hidden component may affect the enabled/disabled state of options in following components.
* Fix - Cost of Goods for 'Priced Individually' composited items stored incorrectly when calling 'WC_CP_Order::add_composite_to_order'.
* Tweak - Renamed 'Activate Configuration' to 'Activate Options'.
* Tweak - Replaced '$.each' with native JS functions.
* Tweak - Revised JS step/component inheritance patterns.
* Tweak - Revised front-end text strings that included the word "configure/configuraton". For example, "Your Configuration" is now "Your Selections".
* Dev Feature - Ability to autoselect attribute values when the available variations are limited by scenarios and only 1 option remains.
* Dev Feature - Added 'woocommerce_composite_component_filter_attributes_args' filter.