Function: galoissubfields
Section: number_fields
C-Name: galoissubfields
Prototype: GD0,L,Dn
Help: galoissubfields(G,{flag=0},{v}): output all the subfields of G. flag
 has the same meaning as for galoisfixedfield.
Doc: outputs all the subfields of the Galois group \var{G}, as a vector.
 This works by applying \kbd{galoisfixedfield} to all subgroups. The meaning of
 \var{flag} is the same as for \kbd{galoisfixedfield}.
