* Fixed: waitlist count sortable columns not showing all products
* Fixed: shortcode not working for variations
* Fixed: waitlist column not reliably sorting by amount of users on waitlist
* Added postmeta for waitlist count for all products to reliably store amount of users on waitlist
* Added function to update postmeta for waitlist counts if they don't exist
* Added functionality for variable and grouped products to reliably store a count for child waitlists
