[Actions] Prepare method added to actions, if they have something to prepare but potentially needs result from other simultaneous actions.

prepare is called only at the first execution, and just before do for each action.
[Players] When the president title changes, the quorum cards go with it.

These cards are automatically shuffled so the new president can't know the previous order of the cards.
The Shuffle action has been upgraded to permit the shuffling of the player cards.