pryce_mating() now allocates a fixed-length structured array, if there's enough memory, instead of using Python lists for the pedigree. I think that some of the slow performance with large pedigrees is due to memory segmentation with large lists. This is an attempt to speed-up the slowest step in the subroutine. I'm still benchmarking to see if it makes much difference. If the array can't be allocated, the program falls-back to using lists.