Clojurians Log v2

So, I'm quite optimistic about using Joker's ns-sources to load libraries from the Internet; I think it could be improved (direct support for sources from GitHub, for example) ... much like the variants supported by Clojure deps.edn dependencies. However, I am concerned about dependency hell; I think a good convention would be that extensions should not, themselves, use ns-sources, but should be self contained. That being said, I'd love to have a port of better-cond https://github.com/Engelberg/better-cond available and this feels like something that could be a built-in library, rather than an external, since it's something small, well understood, generally applicable, etc. Happy to put together a PR.