Primitive Polynomials

Hello,

I would like to have an option for ffgen to return a primitive
polynomial rather than just some random irreducible polynomial.
Preferrably a Conway polynomial but, for many use cases,
any will do.  Would that be hard to implement?  Pari could
iterate through irreducible polynomials until Mod(x,candidate)
has maximal order.  Please excuse me if that functionality is
already present somewhere but I didn't notice.

Cheers,
Martin