Incluision of ideals

[pedritomelenas]

As for now, inclusion of ideals detects ambient semigroups of each ideal. If they are different, then the output is false. This means that it may happen that one ideal is included in another (as sets), but still the output is false, because the ambient ideal is different.

I still do not know if this is the best possible option. From an ideal viewpoint, I would accept it... but IsSubset means "elementwise".