The Contiki network configuration is loaded from the
binary file contiki.cfg having the following format:
- Bytes  1 -  4: IP Address     (HiByte first)
- Bytes  5 -  8: Subnet Mask    (HiByte first)
- Bytes  9 - 12: Default Router (HiByte first)
- Bytes 13 - 16: Unused
- Bytes 17 - 18: Ethernet card I/O address (LoByte first !)
- Bytes 19 - xx: Ethernet card driver name (PETSCII)

The following C64/C128 Ethernet cards are supported:
- RR+RR-Net: Driver cs8900a.eth  with address $DE08
- TFE:       Driver cs8900a.eth  with address $DE00
- ETH64:     Driver lan91c96.eth with address $DE10
