- add -s parameter to start immediately / skip prompt / run non-interactive
This is useful if the user wants to automate the process of updating the user.js and cleaning prefs.
- fQuit: error messages to stderr
- fFF_check: info msg to stderr
Better support for suppressing/redirecting stdout while still showing any error messages in the console, useful for example with `prefsCleaner.sh -s >/dev/null`