Add fmpz_poly_mat or nmod_poly_mat support?

[fingolfin]

In Hecke there is some minimal code to implement support for fmpz_poly_mat. There is nothing for it in Nemo.

Is this something we have any application for, and thus should have someone look into implementing support for?

The same question also applies to nmod_poly_mat, though I don't think we have anyone ccall that code.

Of course if we have no immediate support for either, there is no point in wasting resources on it. I just would like to make sure it is a conscious decision, not an accidental oversight :-).