2017.03.09 - version 1.1.0
* Feature - Added a setting to make the delivery date an optional, required or auto-generated field in the checkout form.
* Fix - Missing delivery info in the 'customer_on_hold_order' emails.
* Fix - Display always the 'Delivery Date' column before the 'Date' column in the order list.
* Fix - Fixed the appearance of the 'help tips' icons on the settings page.
* Dev - Added plugin constants.
* Dev - Deprecated 'dir_path', 'dir_url', 'date_format', 'date_format_js' and 'prefix' properties in the main class.
* Dev - Updated bootstrap-datepicker.js library to the version 1.6.4.
* Dev - Added wc-od-datepicker.js script to abstract the datepicker library.
* Dev - Checkout class rewritten to make it more extensible by developers.
* Dev - Set the minimum requirements to WP 4.1+ and WC 2.5+.
* Dev - Moved class loading (autoload) code to the 'WC_OD_Autoloader' class.
* Dev - Refactored singleton pattern code in the 'WC_OD_Singleton' class.
* Tweak - Added compatibility with WooCommerce 2.7.
* Tweak - Removed Select2 and jquery.BlockUI assets. It only uses the libraries included with WooCommerce.
* Tweak - Added the template 'emails/email-delivery-date.php' to display the delivery details on emails.
* Tweak - Updated the templates 'order/delivery-date.php' and 'checkout/form-delivery-date.php' to make them more customizable.
* Tweak - Avoid duplicate numbers when displaying a delivery range with the minimum value equal to the maximum value.
* Tweak - Added singular string for the delivery range text displayed in the checkout form.
* Tweak - Use the global variable '$wp_locale' to fetch the weekdays strings in the function 'wc_od_get_week_days'.
* Tweak - Use the timezone of the site instead of UTC for all the date operations.
* Tweak - Added hooks to customize the calendar styles.