WooCommerce Pre-Orders 2.1.0

* Add - Blocks integration.
* Tweak - Bump supported WC Version.
* Tweak - Bump tested up to WP Version.

* Fix - Jquery deprecated code.
* Tweak - Jquery 3.0 compatibility.
* Tweak - Improve performance of scheduled action that completes orders after product is released.
* Fix - Use WooCommerce order details template instead of a custom one.
* Fix - "Your previous cart was emptied" message does not show when using ajax cart.
* Fix - Error message on Pre-Orders list when a product pre-order is disabled.
* Fix - Broken email links when sending links via WooCommerce > Pre-Orders > Actions.
* Tweak - Pre-Orders table under My Account > Pre Orders responsiveness
* Fix - Stock inventory is not replenished when a pre-order that's set to charge "Upon Release" is canceled.
* Tweak - Pre-load product when clicking on "Use the actions menu" to change the release date.
* Add - Allow to search for Pre orders only and Regular orders only on WooCommerce > Orders.
* Fix - Refunded orders are counted as Net Sales in WC > Reports when Pre-Orders is active.
* Tweak - Prevent listing pre-orders when they must be paid upfront and the payment fails.
* Tweak - Rename the .pot file so it matches the registered text domain.
* Add - Add fees to order when creating via admin.
* Fix - Reduce inventory for 100% coupon payments.
* Fix - Complete the product's release process when the release date is updated to the past and pre-orders exist.
* Tweak - Make the notice for when the cart contains a pre-order be of the 'error' type.
* Add - Add an option to enable product Pre-Order automatically when stock hits zero.
* Fix - Email message when order is on-hold.
* Tweak - Prevent multiple pre-order products to be added on order created via admin.
* Fix - "Release Date Changed" email mentions it changed to a future date when it's set to the past.
* Tweak - Pre-Orders status counter performance improvement

* Fix - Prevent fatal errors when loading WC Subscriptions admin reports. PR#272