converted all uses of list to set in ChessBoardMatcher
removing all old uses to chessPieceLookup. Since there are many references that need to converted, temporarily using ChessPieceLookup class to ease in the transition
moved subsetManager to GameManagerImpl as there is no real reason to have it in the Game class which is is more to just keep state
the game object should have knowledge of what its chess piece objects are
no need to distinguish between Game and GameState
moved handlecapture, handlecheck, handlegameover and similar methods out of pgninterpreter and into the regular gamemanagerimpl because they do not deal with pgn parsing
renamed GameManager to PGNViewer
renamed GameManagerImpl to GameManager because it's no longer implementing an interface or using the proxy manager model
deprecated ChessPieceLookup and removed private variable chessBoard from PGNInterpreter in order to eventually move the code to PGNViewer
first draft of PGNViewer implementation, moved subset manager back into Game class