Gah. I think I just programmed my way into a corner

Just commiting to revert back to a previous state.
Revert "Gah. I think I just programmed my way into a corner"

This reverts commit 94b6390624f7b995413fad16c02eda0631f436f7.
Piles!

Groups of cards that don't make up a full deck are called piles.
std::vector<Card> is a pile

I haven't thought about how to turn that into code so it's more of a
naming convention.

Anything referring to a pile means just one pile.
Anything referring to a deck means all piles in the deck.