Optimalisation and reducing number of relations between Server and
ClientThread (GRASP)
Deck is Singleton class from now on
Deck is no longer stored directly in Server class
Deck is accessed via ClientThread class on a server-side
pullCardToString was implemented in Deck class
Server now uses pullCardToString in order to follow Low-Coupling pattern
UML scheme was updated
Bot & Human classes no longer appeal to Hand
Fix conflicts