YITH WooCommerce Ajax Product Filter Premium 5.5.0

* New: Support to WooCommerce 3.6
* Update: Plugin Core Framework
* Fix: undefined variable term_id in attributes table

* Fix: Wrong reset page with WooCommerce Filter by price widget
* Fix: Support to Aurum theme - Filter issue using AND operator
* Update: Plugin Core Framework
* Update: All language files (Italian, Dutch and Spanish)
* Tweak: New Widgets name
* Dev: yith_wcan_unfiltered_args hook to manage the unfiltered args for get_posts
* Dev: yith_wcan_skip_no_product_count_bicolor hook to skip show bicolor wit no products

* New: Support for WordPres 5.0
* Tweak: Option description
* Fix: Undefined index: source_tax in YITH Reset Filter widget
* Fix: Issue with reset filter in product categories page
* Dev: new parameter for filter 'yith_wcan_dropdown_label'