Add arbitrary record separator

[birchb1024]

brekbrek says: One suggestion: it may help to generalize the newline as the node separator. You may already be doing this (my go is rusty) but instead of https://github.com/birchb1024/frangipanni/blob/7543b4ee15ae7... be able to override the "newline" as the node separator, like you've done with the "spacer" param.