Function: rnfkummer
Section: number_fields
C-Name: rnfkummer
Prototype: GDGD0,L,p
Help: rnfkummer(bnr,{subgroup},{deg=0}): bnr being as output by bnrinit,
 finds a relative equation for the class field corresponding to the module in
 bnr and the given congruence subgroup (the ray class field if subgroup is
 omitted). deg can be zero (default), or positive, and in this case the
 output is the list of all relative equations of degree deg for the given bnr

