Clojurians Log v2

🙏 Thank you Nathan!

@lidorcg zippers are not very performant

but if you need to do things like walk back up the tree after having walked down, they're useful

a recursive path with Specter rivals hand-optimized traversal code

this benchmark is of a similar use case: https://gist.github.com/nathanmarz/b7c612b417647db80b9eaab618ff8d83#file-results-clojure-1-7-0-clj-L88