subgroups support in some galois* functions in CVS

[Bill Allombert <allomber@math.u-bordeaux.fr>]

Hello PARI-dev,

The following functions, 
galoisisabelian, galoisexport, galoisidentify and galoissubgroups
now accept subgroups output by galoissubgroups() as input (but 
still accept Galois groups output by galoisinit()).

For example you can do:
G=galoisinit(P);
L=galoissubgroups(G);
vector(#L,i,galoisisabelian(L[i],1))
vector(#L,i,galoisidentify(L[i]))

Cheers,
Bill.