todo
 - implement the login using connect button in the GUI
 - implement the use of a configuration file for the GUI:
    - remember multiple login credentials
    - remember program status (activated tab etc.)
 - set Portnames in GUI switchbox according to the name given to the port
 - implement the watchdog functionality (representation in port class)
 - implement the timer functionality (representation in port class)
 - maybe cleanup of the public methods of the netio230a class?
 - type safety!!!

done
 - implemented all documented commands found in the manual up to command "port" on page 19.
 - much more ...

