Refactor chessBoard.js
separated chessBoard.js in two files: chessboard/chessboard.js and chessboard/defaultConfig.js
chessboard.js included builder and run chess, defaultConfig included the default configuration of chess
separated chessBoard.js in two files: chessboard/chessboard.js and chessboard/defaultConfig.js
chessboard.js included builder and run chess, defaultConfig included the default configuration of chess