WooCommerce Composite Products 9.0.4

* Important - WooCommerce 3.0 support added.
* Important - WooCommerce 2.4 support dropped.
* Dev - 'WC_Product_Composite' refactored based on the core CRUD pattern (WC 3.0+ only). Type-specific data is now handled using getters/setters and a dedicated data store class, 'WC_Product_Composite_Data_Store_CPT'.
* Dev - Create/update/delete Components and Scenarios directly on 'WC_Product_Composite' objects using 'WC_Product_Composite::set_composite_data' and 'WC_Product_Composite::set_scenario_data' (WC 3.0+ only).
* Dev - Introduce basic unit tests for 'WC_CP_Order' and 'WC_Product_Composite' classes.
* Feature - Create composite products using the REST API '/products/' endpoint (WC 3.0+ only). Read more at docs.woocommerce.com .
* Feature - Add composite products to orders using the REST API '/orders/' endpoint (WC 3.0+ only). Read more at docs.woocommerce.com .
* Tweak - Support select2 v4 (WC 3.0+ only).
* Tweak - Simplify price filter widget meta query.
* Fix - Scenarios are now taken into account when calculating composite product price strings (PHP 5.5+ required).
* Fix - Weight of composite products in shipping packages does not include the weight of bundled products physically packaged in a bundle that is itself physically packaged in its parent composite.
* Fix - Prevent infinite loop with plugins calling 'WC_Product::get_sale_price' from a function hooked into 'woocommerce_get_price'.
* Fix - JS app: Validation messages are not added to components when the current product/variation selection in a component is invalid.
* Fix - JS app: Always pass validation and hide notices if a component is invisible/hidden or its quantity is zero.
* Fix - Infinite loop when viewing an order that contains a composite set to be preordered using the WooCommerce Pre-Orders extension.
* Fix - Sold Individually > "Matching configurations only" option not working correctly.
* Fix - Missing semicolon in inline JS declared in 'WC_CP_Display::enqueue_composited_table_item_js'.
* Fix - Issues with navigation when using the Componentized layout and conditionally hidden components exist.
* Fix - Component indentation in cart is not preserved after refreshing cart contents.

* Fix - Database upgrade from v3.6.x unable to complete when migrating many composite products due to an issue with update function 'wc_cp_update_370_main' that caused it to stop and restart indefinitely.
* Fix - Incorrect Composite total reported in the single-product page caused by including subtotals of invisible/hidden Components.
* Fix - Empty price string showing up when a composite without a base price contains optional-only, individually-priced components. Price string is now correctly showing up as "From: $0.00".
* Dev Fix - Prevent stock validation when adding composites to orders using 'WC_CP_Order::add_composite_to_order'.
* Tweak - Components that are physically packaged in a composite now show up as individual options of their parent in Shipstation packing slips. Previously, they were all listed in a single "Contents" field.
* Tweak - Components hidden conditionally using Scenarios are animated when removed/added (Stacked and Progressive layouts).

* Dev - Added 'scroll_viewport_top_offset' field to 'wc_composite_params' front-end script parameters. Use it to define an auto-scroll top offset in order to resolve issues with floating top bars partially hiding content when auto-scrolling - e.g. when bringing a new Component into view (Stepped/Componentized layout). Modified using 'woocommerce_composite_front_end_params'.
* Fix - blockUI spinner not spinning.
* Fix - Updated version in main plugin file.