[Feature Request] Diffing two decks

I often am running a few different variants of a single deck (e.g., splashing different colors), so it'd be hugely helpful to be able to generate a list of cards to remove and add in order to change one deck into another.

It'd also be great if you could generate a list of cards that you don't already own from a deck list that could be copy/pasted into the TCGPlayer deck builder or similar.