Basic game logic.

...all 52 card values stored as strings (first character for the card value, second character for the suit); it creates varaibles for both player decks, both draw piles, and both in-play (center) cards. This commit also contains a shuffleDeck function which randomly rearranges the order of the cards in the mainDeck array, as well as a dealCards function which distributes the cards from the mainDeck to each of the other decks.