func (f *Field) MovePieceToLeft(piece *Piece, x, y int, angle Angle) int {
	if piece.collides(f, x-1, y, angle) {
		return x
	}
	return x - 1
}
func (f *Field) MovePieceToLeft(piece *Piece, x, y int, angle Angle) int {
	if piece.collides(f, x-1, y, angle) {
		return x
	}
	return x - 1
}
// MovePieceToLeft tries to move the piece to the left
// and returns the piece's next x position.