
    !   this is a major bug and/or lack of functionality and should be fixed
        ASAP.
    +   this is potentially useful enchancement.
    -   minor improvement.


 So, current TODO is:

    !   talk to syslog
    !   add 'step' to config-based version.
        idea: user can specify differrent step value for every rule.
        sysfence computes GCD of all stepping values, uses it in sleep(), but
        checks rules only when needed.
    +   port to *BSD family and other UN*X systems. I neither know nor use any
        of them, so every help is welcome.
    +   talk to syslog. Give info about exceeded limit and command execution
        result. With some debug option, report all stats every step seconds.
    -   optionally, die after first execution of given command..

