CyclicExtensionsTom( tom, p )
According to A.~Dress Dre69, two columns of the table of marks
tom are equal modulo the prime p if and only if the corresponding
subgroups are connected by a chain of normal extensions of order p.
CyclicExtensionsTom returns the classes of this equivalence relation.
This information is not used by NormalizerTom although it might give
additional restrictions in the search of normalizers.
gap> CyclicExtensionsTom( a5, 2 );
[ [ 1, 2, 4 ], [ 3, 6 ], [ 5, 7 ], [ 8 ], [ 9 ] ]
GAP 3.4.4