public function getFitness():Number
The scale of this number is arbitrary. 0-1 will work just as well as -100000 - 100000 or other range
Used directly in Roulette selection with proportional selection,
but only in ranking for default Tournament selection.
You can define a different EvolvableComparator for Tournament which does not use this at all.
Returns public function getGenome():Genome
gets the genome used to generate this evolvable, and mutate/combine to create a new genome for next generation
Returns