BoardGamesEngine exectuble

[oggy22]

Convert BoardGamesEngine into executable so it can be used to play games, for example:
BoardGamesEngine.exe chess -player1:depth=8 -player2:depth=10
BoardGamesEngine.exe chess -player2:depth=10,eval=material
BoardGamesEngine.exe connect4 -player2:depth=10 play against computer with depth=10 and empty eval function.

player1 and player2 if not specified are played by the user. For example: BoardGamesEngine.exe chess will prompt user for all white and black moves.