WooCommerce Product Bundles 8.3.5

* Fix - Updated add to cart validation for Bundles with Subscription items when manual renewals are enabled.
* Fix - Bundled product attributes are not listed correctly in parent Bundle pages under WC 3.6+.
* Fix - Emogrifier error caused by an unrecognized selector.
* Dev Tweak - Introduced 'WC_Bundled_Item::get_bundled_item_display_attribute_args'.

* Important - Dropped support for WooCommerce 3.0.
* Important - Added support for WooCommerce 3.6+.
* Tweak - Removed old WooCommerce Helper dependencies.
* Fix - Added support for Composite Products 4.0.
* Fix - Bundled product Add-Ons not added to cart when the parent Bundle is part of a Composite.
* Fix - Prevent chosen bundled variation image from showing when optional bundled product is not selected.
* Fix - Use 'Override Default Selections' in combination with 'Filter Variations' to lock down attributes even when 2+ variations are enabled in 'Filter Variations'.
* Fix - Prevent out of stock bundle-sells from being selected.
* Fix - Fatal error when viewing the "Reports > Stock > Insufficient Stock" report and orphaned bundled items exist in the DB.

* Feature - Added support for bulk editing Regular/Sale price of Bundles.
* Tweak - Added 'woocommerce_editing_bundle_in_order' action, triggered after editing a bundle in an order. Useful for porting over old item meta.
* Fix - Added compatibility with ThemeAlien Variation Swatches for WooCommerce.
* Fix - Strikeout price of optional variable bundled product with discount missing in some rare cases.
* Fix - Remove 'x items left' from availability text when bundled item stock quantity is less than zero.
* Fix - Incorrect relative prices of Bundles in Composite products.