Function: nfeltreducemodpr
Section: number_fields
C-Name: nfreducemodpr
Prototype: GGG
Help: nfeltreducemodpr(nf,x,pr): element x modulo pr in nf, where pr is in
 modpr format (see nfmodprinit).
Doc: given an element $x$ of the number field $\var{nf}$ and a prime ideal
 \var{pr} in \kbd{modpr} format compute a canonical representative for the
 class of $x$ modulo \var{pr}.
Variant: This function is normally useless in library mode. Project your
 inputs to the residue field using \kbd{nf\_to\_Fq}, then work there.
