GetFitness override should pass in previous cBots instances

So the idea is that during optimization I should be able to get all the previously tested cBots with all their Parameters and GetFitnessArgs.

        protected override double GetFitness (GetFitnessArgs args)
        {
            IEnumerable<PreviousBot> previousBots = args.PreviousBots;

            ...
        }

The idea is to again, to generalize GetFitness with new metrics.