Function: nfhilbert
Section: number_fields
C-Name: nfhilbert0
Prototype: lGGGDG
Help: nfhilbert(nf,a,b,{p}): if p is omitted, global Hilbert symbol (a,b) in
 nf, that is 1 if X^2-aY^2-bZ^2 has a non-trivial solution (X,Y,Z) in nf, -1
 otherwise. Otherwise compute the local symbol modulo the prime ideal p

