Function: galoisisnormal
Section: number_fields
C-Name: galoisisnormal
Prototype: lGG
Help: galoisisnormal(gal,subgrp): gal being as output by galoisinit,
 and subgrp a subgroup of gal as output by galoissubgroups,
 return 1 if subgrp is a normal subgroup of gal, else return 0.
Doc: \var{gal} being as output by \kbd{galoisinit}, and \var{subgrp} a subgroup
 of \var{gal} as output by \kbd{galoissubgroups},return $1$ if \var{subgrp} is a
 normal subgroup of \var{gal}, else return 0.

 This command also accepts subgroups returned by \kbd{galoissubgroups}.
