 - improve the setting of the serial port (thats *REALLY* a hack ;-)
 - use ioctls instead of system programs to set the serial port
 - use flock() to make sure the prot is only used by the calc (I am not
     sure if this is really required...)
 - implement the hp crc xmodem protocol instead of using "sx"
 - add a fork or thread or someway to show updates in window when using
     GUI (whatever will be obsolete by changes in comm system)
