[HierRR/Hier3RR]: Fixed boundary-condition segfault

Fixed a segfault in HierRR and Hier3RR that arose when no paths at all
were present (i.e. the genome being examined had an overall fitness of 0).

Signed-off-by: Sebastian Lenartowicz <slenarto@uoguelph.ca>
[GAGeneration]: Fixed potential segfault

Fixed an occasional segfault in GAGeneration that arose from a condition
where all the fitnesses in the population were 0, which would result in a
value never being initialized.

Signed-off-by: Sebastian Lenartowicz <slenarto@uoguelph.ca>