Running `npm install` without `--no-save` can introduce spurious changes to package-lock.json due to differences in platform / node version, and these have been known to accidentally sneak into people's PRs. `npm install` without `--no-save` should only be used when actively updating node dependencies in package.json.
This is the correct lexer for interactive console sessions, according to
<http://pygments.org/docs/lexers/>. This does require command lines to
be prefixed with `$`, otherwise they are interpreted as the output of a
command. It highlights the command nicely, including environment
variables, strings, and comments.
