Barn2 Media - WooCommerce Bulk Variations 2.4.3

* Fix: Resolved fatal error when WooCommerce is not active

* Fix: Resolved incorrect stock availability markup output
* Fix: Resolved missing columns/rows when attribute terms are equivalent in a loose comparison (e.g. "0" and "00")
* Dev: Code refactoring

* Fix: Resolved issue with Quick View Pro lightboxes being closed unintentionally.
* Fix: Resolved issue with 'Add to Cart' button never enabling when all variation quantities default to zero.
* Fix: Resolved issue with variation grid not appearing when every variation is out of stock.