Make nf_elem_set support unreduced nf elements

[wbhart]

trafficstars

In the Matrix and Poly modules, we read coeffs/entries, do an accumulation then write the accumulated result (this hack is a hack we introduced some time ago). This would all support delayed reduction if only the setting of the coeff/entry at the end of the accumulation supported setting of unreduced elements.

At present, in Antic, we only support addition and subtraction of unreduced number field elements.

This would have to be supported in Antic itself, and documented for any other module that was designed to support delayed reduction.

[fredrik-johansson]

It's also possible to introduce dot product functions for this (like in Arb).

[wbhart]

Yes, although our generic code would not be able to use them.