* Add support for runtime update of DHCP packets that contain HW
addresses (some routers wouldn't assing IP if the MAC was spoofed
only in Ethernet and ARP frames)
* Simplify Ethernet initialization using default eth-netif glue
* adds description about that it's not a bridge, but more like an 1:1
forwarder on L2
* add and describe mac spoofing for Ethernet interface
* describe virtual networking for USB-NCM interface