An attempt at a weird way to add a new deck

Doesn't work without a fairly chunky change to how cards are fetched.
Seeing as this is examination material, that's not wanted
Revert "An attempt at a weird way to add a new deck"

This reverts commit f836c52c923568d5fbda27ef44cc02a95a12d540.
Deck size increased to 2 decks

Essentially, increase the size of the array, account for this in
LoadDeck, and use Deck.Count most places