Allow DHCP/BOOTP renewal on CIP Type 0 reset. Major rework of netif handling

The idea is to allow proper renewals of a previously obtained DHCP/BOOTP lease at a specific server in case of type 0 reset or BusOn->BusOff->BusOn state transition.

This is in conjunction with our other efforts to keep the netif up in regular scenarios, i.e the BusOff state is already implemented in Protocol-specific fashion where it previously set the netif down.