cmd()
  A realscanner used to scan over command line programs.
  
  Usage: cmd(['command','arg1',...],StatusCLEAN,StatusINFECTED,RE)
  
  Where: 'command' is a string, which command to run
         'argX' are command line arguments, as last argument the
           filename is added
         StatusCLEAN may be:
           an array of integers, which defines "clean" exit codes
           an regexp, indication no virus found
         StatusINFECTED may be:
           an array of integers, which defines "virus found" exit codes
         RE is an regular expression string, which can extract virus
           names from scanner output.