Function: nfmodprinit
Section: number_fields
C-Name: nfmodprinit
Prototype: GG
Help: nfmodprinit(nf,pr): transform the 5 element row vector pr representing
 a prime ideal into modpr format necessary for all operations mod pr in the
 number field nf (see manual for details about the format).
Doc: transforms the prime ideal \var{pr} into \tet{modpr} format necessary
 for all operations modulo \var{pr} in the number field \var{nf}.