So I think there is an inherent problem with our selection methods. For methods like rank-based selection, I think we need to be returning a set of pairings of individuals, instead of just a single pairing of individuals.. The reason for this is because methods like rank-based are reliant on the population as a whole, not on two individuals (as is now).. This is difficult to explain in writing.

In any case, I think we should change selection a bit.

Signed-off-by: cauth0n <derek.reimanis@gmail.com>