IMPORTANT: Danny, ask about addBlock

Crossover got better: CutAndSplice is now working properly. Also,
Crossover no longer excludes *both* children if one failed the
Creature-instantiation test (doh). This change and the addition of
HillClimbing’s working AddBlock are significant enough that I was able
to remove the random reseeding every 50 generations. I left the method
in case we need it again.

Calling Genotype’s addBlock or addRule now has the option of passing in
a Crossover module to provide instantiation weights for the newly
created Alleles. Danny needs to explicitly implement this.

*Slightly* increased the size of the random creatures. They’re now 5-12
blocks.