Lem: Editor/IDE well-tuned for Common Lisp

I've been following the commit logs of this for awhile, and I'm really impressed by how active it consistently is. I think most people who aren't deep into Emacs might not realize _how_ monumental a task it is to be competitively featurful and configurable. But I actually believe that Lem is getting there! And it can already evaluate a considerable amount of elisp, such that `calendar-mode` from vanilla Emacs can simply be run inside of Lem.

I've given this a quick try. One observation is that it is very fast.

The other is that I have much muscle memory about keybindings for emacs that are both from built-ins and code that I have written.