Fix board rendering by moving it into game loop
Fix valid move checking
Fix moving_sideways check for pawn moving
Fix valid_move? method for Pawn class
Fix has_players_piece method
Fix piece retrieval in game loop
Fix boundary checking
Fix move input
Reset terminal before each board render
Add support for storing and displaying lost pieces
Break valid_move? into valid_move? and possible_moves for all Pieces except Pawn
Fix valid move checking
Add support for checking if either player is in check
Add support for checking if a player is in checkmate, and ending game if so
Change board.render to be to_s instead
Fix checkmate checking code
Remove unnecessary methods
Fix valid moves checking
Make it so that you can only make moves to get out of checkmate when in checkmate
Add support for pawn promotion