adds ChessBoard#checkmate?
adds .gitignore file
Adds exceptions to ChessBoard#move, adds HumanPlayer#play_turn
Adds Game#play, which loops until game over
Adds unicode hash to ChessBoard
Adds colorize, starts ChessBoard#render
Completes ChessBoard#render
Changes ChessBoard#render, and finishes game
Completes chess, Refactors code