Revised gateway demo to use the new device_init(NULL) way.
Eliminated triplicate I-Am responses and deprecated the offending routed_ I-Am and I-Have senders (don't see any other usages; scheduled for deletion in 2/2012).
Fixed I-Am sender to not always zero out dest->net, because if a src->net was given in Who-Is, need to have it or else global bcast in the I-Am response.