OK, I see the problem. It was based on a misunderstanding of the GroupedProblemForm.evaluate
parameters. I thought that the ind array would have ind the individual under evaluation, and ind
 the opponent. That's how it was when I only had one subpopulation and was running the
I switched to MultiPopCoevoluationaryEvaluator, figuring it would do the same thing, but it doesn't.
Apparently the ind array is the size of the number of subpops, and the update element that's true
is the individual under evaluation.
Now the only problem is that it seems that ind is always an individual from subpop 0, ind is an
individual from subpop 1, and ind is one from subpop 2. What I really wanted was to choose a
random individual from a random subpop (not in my own subpop).
I guess that means that in my GPProblem's evaluate method, I will have to randomly choose one of
the non-updated ind's.
It would be nice to be able to choose the number of opponents in the parameters for