Starts a dev loop using clojure.tools.namespace.repl/refresh in order to restart the app without restarting the JVM. Also starts an nrepl server which will keep up even between app crashes and restarts.

In case of an error, the console prints WAITING FOR RESTART and the /restart! function will restart the app and call refresh.

You can bind this on a key for smooth dev experience, here in VIM:

nmap <F5> :Eval (do (in-ns 'gdx.dev)(restart!))