improvement: add validation to catalog visibility field
improvement: match cross-sell products by title
API: new filter wp_all_import_get_prices_from_first_variation
API: new filter wp_all_import_variation_any_attribute
API: new filter wp_all_import_product_attributes_delimiter
bug fix: images not imported to first variation when 'WooCommerce Additional Variation Images' plugin is installed
bug fix: shipping class not imported properly in some cases
bug fix: prices for variable products with 1 variation are not imported in some cases
bug fix: product_visibility taxonomy for product variations not imported in some cases
