Server: refactoring: use enum for pieces
Server: refactoring: separated ClientDataParser from Servlet
Server: AI choose hand which promotes or captures
Server: added score to each piece type for AI to capture better piece
Server: Game is singleton but Board is not singleton
Server: Board implements Cloneable and used by calcNextPlayerScore
Server: AI reads next player's hand except captives
Server: AI calculates score when playing captive as well