Specifies which hyperplane arrangement to consider. By default (or by
explicitly entering "mct") it supplies the standard "Modal Color Theory" arrangements
of getineqmat(), but can be set to "white," "black", "gray", "roth", "pastel," or "rosy",
giving the ineqmats of make_white_ineqmat(), make_black_ineqmat(), make_gray_ineqmat(),
make_roth_ineqmat(), make_pastel_ineqmat(), and make_rosy_ineqmat(). For other
arrangements, the desired inequality matrix can be entered directly.