Highlight eval, kaocha testing and various fixes!

Hello everyone! I hope you're all having a good week, I'm on a two week break from work and I've accidentally spent a lot of it working on Conjure. Oopsie! That means you all get a new Conjure version though, so yay! Now onto the changes 🎉

• Merge #193 - adds optional highlighting of evaluated forms, requires Neovim 0.5+ (nightly builds) and the option enabled, check out :h conjure for information on this if you're interested. It works really well! Thank you for submitting it @taw10!
• Fixed and documented some configuration options for the stdio clients, should make using different Scheme REPLs easier (#199, #198).
• Handle long form metadata in deftest forms in Clojure when running the current test #196
• Created my own fennel.vim syntax fork and linked to it from the docs. It includes a few outstanding PRs against the upstream repo as well as support for Aniseed's module macro symbols. I may include this in Conjure + Aniseed by default in the future so you don't need to worry about Fennel support in your editor.
• Support kaocha with Clojure's testing mappings for #188! See :h conjure-client-clojure-nrepl and that issue for the setting you need to change. It has the exact same mappings, but it'll run the tests through kaocha instead of clojure.test!
• Handle stdio REPLs failing to start due to not being installed etc. It'll now tell you what went wrong instead of pretending everything is fine #197.

Have a wonderful weekend, get some rest, you're doing great.