code: private int mutateColourComponent(int component)
      {
          int mutatedComponent = (int) Math.round(component + mutationAmount.nextValue());
          mutatedComponent = Maths.restrictRange(mutatedComponent, 0, 255);
          return mutatedComponent;
      }
docs: Adjust a single component (red, green, blue or alpha) of a colour.
  @param component The value to mutate.
  @return The mutated component value.