* Feature - Charge an additional cost (delivery fee) for choosing specific delivery days and time frames.
* Tweak - Removed the option 'auto' in favor of the option 'required' in the 'Delivery fields' setting.
* Tweak - Hide the delivery fields in the checkout form when there are no available dates.
* Tweak - Keep the delivery fields' values when refreshing the checkout form.
* Tweak - Prevent the interaction with the delivery fields while the checkout fragments are being refreshed.
* Tweak - Validate the 'Delivery days' form field is not empty when adding a time frame to multiple delivery days.
* Tweak - Display the info 'Number of orders' in the 'Description' column of the 'Delivery days' setting table.
* Tweak - Don't display the delivery estimation text when the range of days is zero.
* Tweak - Added a link to get support in the plugin list.
* Tweak - Improved formatting of the System Status Report.
* Tweak - Tested compatibility up to WC 6.5.
* Tweak - Tested compatibility with WP 5.9.
* Fix - Fixed a double triggering of the event 'update_checkout' when clearing the value of the delivery date picker.
* Fix - Fixed compatibility issue for PHP 8.1.
* Dev - Use a WC background process to handle the plugin updates.
* Dev - Use a trait instead of a class for implementing the Singleton pattern.
* Dev - Added custom tables for storing the time frames' data.
* Dev - Added data stores for handling the delivery days and time frames.
* Dev - WC Subscriptions v2 is no longer supported.
* Dev - Dropped deprecated plugin code up to version 1.7.
* Dev - Deprecated the access as an array to the data properties of a `WC_OD_Data` object.
* Dev - Deprecated custom setting field `wc_od_day_range`.
* Dev - Updated the minimum requirements to WC 3.5, WP 4.7, and PHP 5.4
