code: public static <C extends Comparable<? super C>>
  	Predicate<EvolutionResult<?, C>> bySteadyFitness(final int generations) {
  		return new SteadyFitnessLimit<>(generations);
  	}
docs: Return a predicate, which will truncate the evolution stream if no
  better phenotype could be found after the given number of
  {@code generations}.
  
  <pre>{@code
  final Phenotype<DoubleGene, Double> result = engine.stream()
  // Truncate the evolution stream after 5 "steady" generations.
  .limit(bySteadyFitness(5))
  // The evolution will stop after maximal 100 generations.
  .limit(100)
  .collect(toBestPhenotype());
  }</pre>
  
  @param generations the number of <i>steady</i> generations
  @param <C> the fitness type
  @return a predicate which truncate the evolution stream if no better
  phenotype could be found after a give number of
  {@code generations}
  @throws IllegalArgumentException if the generation is smaller than
  one.