Change Row's get_guess to get_code_peg_holes, set_guess to set_code_peg_holes, get_clues to get_key_peg_holes, set_clues to set_key_peg_holes; change Human's solicit_clues to solicit_feedback, check_clues to check_feedback
Remove CodePegHole and KeyPegHole classes, integrating their behavior into Row; remove unnecessary validation