Improved IsIsomorphicSemigroup Method

[tillman-froehlich]

Added a better method to compute whether finite simple semigroups are isomorphic which is faster than the current one.

[reiniscirpons]

Looks good, thanks for the PR! One minor change and a question about speedup and were good to merge I think.

[james-d-mitchell]

Just to also add that with this PR:

gap> R := ReesMatrixSemigroup(AlternatingGroup([1 .. 5]),
> [[(), ()], [(), (1, 3, 2, 4, 5)]]);;
gap> S := ReesMatrixSemigroup(AlternatingGroup([1 .. 5]),
> [[(1, 5, 4, 3, 2), ()], [(1, 4, 5), (1, 4)(3, 5)]]);;
gap> IsIsomorphicSemigroup(R, S); time;
15

and without

gap> R := ReesMatrixSemigroup(AlternatingGroup([1 .. 5]),
> [[(), ()], [(), (1, 3, 2, 4, 5)]]);;
gap> S := ReesMatrixSemigroup(AlternatingGroup([1 .. 5]),
> [[(1, 5, 4, 3, 2), ()], [(1, 4, 5), (1, 4)(3, 5)]]);;
gap> IsIsomorphicSemigroup(R, S); time;
117

So this change is definitely worth making!

[james-d-mitchell]

Thanks @awesometillman