Fixed a but in the mysql module, so it builds as write-only module, too.

Fixed a but in the mysql module, so it builds as write-only module, too.
Shorted the command line options to `help' and `dont fork' only.
Brought `getopt' back: `libconfig' doesn't do what I want: Command line options are evaluated after config files. So I don't know what mode the daemon will be in when parsing the file. That's why I moved everything into the config file.
Removed `cf_callback_usage' again.
Changed `cf_read' to not need `argc' and `argv' anymore..