cleans up valid move checking, breaks in_check
fixes in_check? and causes_check?
Fixes checkmate, squashes all bugs found. WORKING GAME
Clean up chess.rb methods
splits methods in chess.rb, and chessboard.rb
Refactor Pawn and spawn_pieces
refactors path
Privatize methods in chessboard.rb
Privatize methods in Game class
Add pawn promotion
Move 'Check' display
Refactor Pawn and Game#path
Cosmetically changes code
fix bug in Game#path, refactor chess pieces
Add Save/Load functionality; refactor UI
Adds operator class, saving game switches turn
fixes save bug