CardArray
 - Update CardArray with a configurable selection limit.
CardManager
 - Update SetCardsSelectable to specify the limit on selectable cards.
GameManager
 - Update GameManager with signal/slot changes.
 - Add a new button to the scene.
StateManager
 - Update StateManager with new connections.
ExchangePhase
 - Update exchange phase signal emits.
DeclarationPhase
 - Updated implementation for initial PlayerPoint stage.