Implements changing a card from piles

- It makes possible to change a card from pile to pile, but it doesn't enforce any game rules yet. NOTE: This will not work when trying to change cards in the middle of the pile, as this will be handled later when groups of cards is implemented. Trying to move a card in the middle will yield unexpected results.
- All revealed cards are now draggable
- Moves cards automatically from stock to waste when a card is removed from the waste.