Function: galoissubfields
Section: number_fields
C-Name: galoissubfields
Prototype: GD0,L,Dn
Help: galoissubfields(G,{flags=0},{v}):Output all the subfields of G. flags
 have 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
 the flag \var{fl} is the same as for \kbd{galoisfixedfield}.
