[Feature Request] "Not" item matching

[ProspectPyxis]

Not sure how viable this would be code-wise, but I'd like a "anything but this item" match, so you can do things like "if item x is in main hand and item y is not in the offhand then set the player on fire", essentially being able to set an item as a "protection" item.

[McJty]

I have something much better in store. I want to implement it so that you can negate any condition

[ProspectPyxis]

That would be awesome to see.