* Fix - Fixed unload prompt not working.
* Dev - Reduced number of queries needed to populate the relationship field taxonomy filter.
* Dev - Added 'nav_menu_item_id' and 'nav_menu_item_depth' to get_field_groups() query.
* Dev - Reordered various actions and filters for more usefulness.
* i18n - Updated Polish language thanks to Dariusz Zielonka
Fix - Fixed bug causing multisite login redirect issues.
Fix - Fixed bug causing validation issues in older versions of Firefox.
Fix - Fixed bug causing duplicate Select2 instances when adding a widget via drag/drop.
Dev - Improved WPML compatibility by using `$sitepress->get_current_language()` instead of `ICL_LANGUAGE_CODE`.
Dev - Improved validation JS with new Validator model and logic.
* Fix - Fixed bug causing field groups to disappear when selecting a taxonomy term with WPML active.
* Tweak - Added more Dark Mode styles.
* Tweak - Improved DB upgrade prompt, functions and AJAX logic.
* Tweak - Improved the "What's New" admin page seen after DB Upgrade.
* Dev - Added new location rules filters.
