Function: bnrconductor
Section: number_fields
C-Name: bnrconductor
Prototype: GDGDGDG
Help: bnrconductor(a1,{a2},{a3},{flag=0}): conductor f of the subfield of
 the ray class field given by a1,a2,a3 (see bnrdisc). flag is optional and
 can be 0: default, 1: returns [f, Cl_f, H], H subgroup of the ray class
 group modulo f defining the extension, 2: returns [f, bnr(f), H]

