The goal is to move the cards from the bottom columns to the four stacks on
the top right corner of the table.

Rules:

   - a card can be moved on top of another card of different color and
     successive value, just like in Klondike.

   - you can move any card on an empty cell.

   - you can move only one card at once: to move a group of them you need
     enough free cells to do the required moves.

   - the four free cells on teh top left corner of the table can hold only
     one card each.
