Removed /chess directory and moved Readme.md to upper directory
Finish Board#move and add Board#move_piece helper
Added Board#dup and Piece#dup methods
Finished Piece#move_into_check? and Piece #valid_moves methods
Add Board#move! and modified Piece#move_into_check? to use #move!
Add Board#checkmate? method
Added HumanPlayer#prompt_for_name method and Game#opposing_color
Begin Game#display_board
Added to_symbol hash
Implemented Game#display_board; Debugged runtime
Added Game#build_move_hash method
Fixed bug and Game#play finally works
Added Exception handling in Game#play_turn; standardized board display; debugged SteppingPiece#moves to account for not attacking contingent pawns of own color
Debugging Board#checkmated? method; in progress
Fixed the Pawn bug and finished chess game.