According to its website, the Ensime project has been shut down since 2019. We
have been supporting both Ensime and Metals for [a year and a
half](https://github.com/syl20bnr/spacemacs/pull/12234#issuecomment-524916394).
Ensime's GitHub repositories, including its Emacs integration, are archived.
Meanwhile, Metals has been developed actively, regularly releasing new versions.
It has stabilized significantly, and supports an increasingly full set of
features. Scala 3 is just around the corner, and the community is poised to make
the transition smoothly and relatively quickly. Metals supports it already,
whereas of course Ensime does not and never will. In fact, Scala 2 has had
several import minor versions released since Ensime died. Now that it's 2021,
it's time to cut the baggage we are carrying around for Ensime.
Helm seems to treat "!" specially in pattern matching, so having a ! in
the pattern string when traversing directories is problematic. This
change fixes#2737, because as far as I can tell "+" has no special
meaning in a helm pattern.
Of course, we can choose a different character, but I'm fond of "+" as
representing "more layers here".
