wip/cask 0.9.0 NetBSD

Cask can be likened to venv or maven for Emacs Lisp development, although, as with all things emacs, is decidedly less sophisticated (but no less arcane).

Cask provisions dependencies within a sandbox via a user-defined "Cask" file analogous to requirements-dev.txt or pom.xml.

Cask does not absolve you of having to learn emacs's command flags. Cask only constructs the sandbox, one for each version of emacs you choose to test.