WooCommerce Composite Products 10.4.0

* Important - WooCommerce 3.1 support added.
* Feature - Added support for importing/exporting composite products using the WC product importer/exporter, introduced in WC 3.1.
* Tweak - Added 'woocommerce_composited_cart_item_name' and 'woocommerce_composited_order_item_name' filters.
* Tweak - Introduce runtime caching of composite price methods' output. Use 'woocommerce_composite_prices_hash' filter if applying price filters conditionally and conditions change during a single request.
* Fix - Error on add-to-cart validation of optional Components when "WooCommerce Name Your Price" is installed.

* Fix - Inconsistent server/client-side price totals in single-product bundle pages due to rounding issues.
* Fix - Inaccurate bundle container item subtotals shown in cart due to rounding issues.

* Fix - Warnings due to use of deprecated 'WC_Coupon' properties under WC 3.0+.
* Fix - Missing contents data of composite product containers and missing child product attributes when importing orders in Shipstation (Shipstation Integration v4.1.13 required).