Add value for `:is-random-replacement` for initial population

[NicMcPhee]

When we added :is-random-replacement to the logged output (a00bde2e82386e9e53e43e816c7f4287403d6329) I didn't notice that that field doesn't have a value for the initial population, which means we have an empty value ("...,,...") in the CSV outputs for the initial population. That's not fatal, but it does mean we'll need to "special case" that when processing those CSV files.

If we were to put a value there, though, It's not obvious to me what would be the "right" value. Should we true (it is randomly generated) or false (it's not a random replacement)? Anyone have any thoughts on this?

[thelmuth]

Make it a non-boolean and set it to :initialization?

Otherwise, I'd go with false.

[NicMcPhee]

Actually, I like that idea. Occasionally I forgot that we're in dynamic typing land and no one requires us to actually use a boolean in a situation like this :-).