API: add wp_all_import_is_post_to_update filter for import variable products from child XML elements
bug fix: unable to block emails to customers when importing WooCommerce orders
bug fix: product default attributes are not updated in some cases
bug fix: unable to update only selected attributes for variations in some cases
bug fix: do not import variation if variable attributes are not defined
bug fix: conflict with woo-advanced-shipment-tracking plugin
bug fix: recalculate taxes and coupons after order imported
