WIP MIL-007: fetch the framework's qc, follow links, default configuration files

- git submodule update --init --recursive after adding or reusing the framework
- Follow links to the script so SCRIPT_DIR and the checkout are the real ones
- config.env and .env: --config/--env, else ./ in the working folder, else the checkout's
- Name the files used; a file from the working folder needs a yes before any request
- MIL-007 accepted; test fixtures for the qc checklists; tests/test-launch.sh

Work in progress: the README section is not written yet, and four tests of
test-launch.sh fail and two shellcheck warnings remain; they are fixed next.

Task: MIL-007#1
Task: MIL-007#2
Refs #47
Refs #48
Refs #51

src/lib/cli.sh

@@ -9,6 +9,8 @@
 usage() {
   cat <<EOF
 Usage: ${0##*/} [--apply] [--config FILE] [--env FILE]
+       Without --config and --env, ./config.env and ./.env in the current folder
+       are read, then the ones in the checkout.
        ${0##*/} --help | --version
 EOF
 }