Add support for 4x4 board
Make better use of Board's copy constructor
4x4 Boards can be printed with CommandlineIO now
Use real Boards for testing Game
Refactored Game output with a golden master
Simplified Board.getWinner()
Refactored commandline output of a Board
Fixed some IntelliJ code inspections
Refactored tests by getting rid of FakeBoard and FakeGame