exit("message") displays a message, but exits with normal error status :(

The script doesn't read configuration at all, usage with same user as web
server is not mandatory, and there is no point at having two different
usage examples, especially if contradictory.

- config files are now in etc subdirectory
- web files are now in www subdirectory
- library files are now in lib subdirectory
- script files are now in bin subdirectory