fixup! Rework option parser to support ‘--’ as escape sequence

If only a single option was given with no arguments (e.g., "$DIALOG" nib --list), we would ignore it.
Write to stdout when using `"$DIALOG" help <command>`

We still write to stderr if the `help` command is called with the incorrect number of arguments.
Write to stderr if «token» does not exist when calling `nib update`