v1.6.4 - Released on 15 January 2021
* New: Support for WooCommerce 4.9
* Update: Plugin framework
* Dev: new action "yith_ywpo_clear_pre_order_product"
* Dev: new filter "yith_ywpo_infinite_scrolling_events"
* Dev: new filter "yith_ywpo_date_format"
