Revert "Enable under-promotions with the CHESS.Board.move() method, e.g. board.move('c8=N'); to promote the pawn to a knight."
Revert "Enable under-promotions with the CHESS.Board.move() method, e.g. board.move('c8=N'); to promote the pawn to a knight."

This reverts commit 903666307db688b6b7bfb188e15be299b98edb21.

ryancookdev/canvas-chess,ryancookdev/canvas-chess