console-watch: check how fast console log files are growing

The program logs on to the console server via ssh and reads the filesizes of
all *.log files. It then sleeps for a given time and reads the filesizes
again. After this it calculates how much the files have grown in that time
and displays the results.

usage: console-watch [options]
  common options:
    -h             : this help
    -t --time TIME : Specify measurement time in seconds, default: 10
    -m --min MINDELTA: 
                     Files that have grown less than MINDELTA are not printed.

  options for retrieving the data:
    -u --user USER : Specify the user for the ssh command, default: conservr.
    -H --host HOST : Specify the console server host, default: conserver.acc.bessy.de.
                     (The mls conserver host is: conserver.mlscs.bessy.de).
    -d --dir DIR   : Specify the directory with the log files, default: /var/log/conserver.

example usage:
  console-watch -t 10 -m 100