YITH WooCommerce Deposits and Down Payments Premium 2.19.0

* New: support for WooCommerce 3.9
* Update: plugin framework
* Update: Italian language
* Update: Spanish language
* Update: Dutch language
* Tweak: prevent plugin from removing custom orders views
*Fix: issue with tax displayed on order details/email* Fix: prevent notice when filtering order items

* New: support for WordPress 5.3
* New: support for WooCommerce 3.8
* Tweak: method that prints additional notes now checks for deposit status with dedicated method
* Update: Plugin framework
* Update: Italian language
* Update: Spanish language
* Fix: prevent notice during cron execution
* Dev: added new action yith_wcdp_deposits_created_notification
* Dev: added new filter yith_wcdp_customer_deposit_created_email_enabled

* New: WooCommerce 3.7.0 RC2 support
* Tweak: cast deposit value to double to avoid "non numeric value" error
* Tweak: add fees on grand total on cart and checkout page
* Tweak: change balance order status to pending payment when deposit order status changed from failed status
* Tweak: add paragraph in deposit and balance payment for show inline block in all webmail clients
* Update: Italian language
* Update: internal plugin framework
* Fix: removed useless yith_wcpb_ajax_update_price_request trigger that used to break js execution on variable products
* Fix: get correct parent product id when a variation is selected
* Fix: expiration days are now added to today's date
* Fix: notice on thank you page
* Dev: added new filter yith_wcdp_show_total_html
* Dev: added new filter yith_wcdp_deposit_print_product_note
* Dev: added new filters for sending deposit expiration email