YITH WooCommerce Advanced Reviews Premium 2.6.0

* New: added Greek language
* New: added the plugin shortcode to the Elementor panel
* Fix: exclude the non rated reviews from the average rating
* Dev: all strings escaped

* New: Support for WooCommerce 3.9
* Update: plugin framework
* Fix: deleted unnecessary schema code for reviews in the reviews shortcode template
* Dev: new filter 'yith_ywar_redirect_after_submit_review'
* Dev: new filter 'yith_ywar_show_review_shortcode_without_product_id'

* Update: Italian language
* Update: plugin framework
* Fix: fixed the issue with the duplicate product short description
* Fix: option panel changes