WooCommerce WishLists 2.3.1

* Update: Cache users lists to prevent duplicate queries.
* Fix: Fix issue where creating new users would assign the administrators lists to that user.

* Update: Send price reduction notifications if an item goes on sale.
* Fix: Fix issue where Wishlists was responding to actions from Duplicate Post plugin. Extension now fully supports Duplicate Posts plugin
* Fix: Fix an issue with PHP 7.1+
* Update: Add header("X-Robots-Tag: noindex, nofollow", true) to the wishlist processing endpoint.
* Update: Add some product checks before attempting to add an item to the list.
* Update: Include a read-only endpoint for Wishlists and Wishlist Items.
* New: Include wc_wishlists_max_user_list_count filter to allow control over how many lists a user can create.

-* Update: Enable order tracking for list items.
-* Update: Update View a List page to include Previously Ordered Count.
-* Update: Update Edit a List page to include Previously Ordered Count.
-* Update: Update Edit a List page to allow editing of Previously Ordered Count.
-* Update: Update WooCommerce -> Wishlists -> Settings to include a toggle for displaying the previously ordered total
-* Note: Order item tracking is enabled in this version, so previous orders will not be present.