quantity.cat for unsorted gridNames
cat(), horzcat(), vertcat() can not be used for quantities with permuted gridNames, for instance [x(z, t), y(t, z)] does not work, eventhough x and y depend on the same gridNames.
cat(), horzcat(), vertcat() can not be used for quantities with permuted gridNames, for instance [x(z, t), y(t, z)] does not work, eventhough x and y depend on the same gridNames.