YITH WooCommerce Color and Label Variations Premium 2.8.1

* Fix: Issue on multi colorpicker
* Fix: Prevent save empty variation gallery
* Fix: Double check image srcset attribute when changing image in archive pages

* New: Support for WooCommerce 3.9.1
* New: Added option to show or hide a single product variation from archive pages
* New: Added option to hide or show variable product from loop
* Update: Plugin framework
* Update: Spanish language
* Fix: No products shown on brands archive page
* Dev: New filter 'yith_wccl_available_variations_loop'
* Tweak: Using transient on archive pages for better performance

* New: Support for WooCommerce 3.9
* New: Support for WordPress 5.3.2
* Update: Plugin framework
* Update: Dutch language
* Fix: Reset term relationship on variable attribute changes
* Fix: Gallery issue with themes that use global post instead of product
* Fix: Show variations in loop also on tax archives and attributes filter
* Fix: Single variation visibility on tax archive pages