Cosmetic changes
snprintf():  If size is zero, then snprintf() should return the size of the required buffer without writing anyting.  From Sami Pelkonen
snprintf():  If size is zero, then snprintf() should return the size of the required buffer without writing anyting.  From Sami Pelkonen
Move arp-related files from net/uip to net/arp
Move include/nuttx/net/uip/uip-arch.h to include/nuttx/net/arp.h; rename all uip_arp_ functions to arp_
Move include/nuttx/net/uip/uip-arch.h to include/nuttx/net/arp.h; rename all uip_arp_ functions to arp_
A few build fixes from last, big ARP relocation change
Move IGMP files from net/uip to net/igmp
Move ICMP files from net/uip to net/icmp
Move ICMP files from net/uip to net/icmp
Move ICMP files from net/uip to net/icmp
Files that I forgot to add in the previous commits
Move arp, icmp, and igmp configuration values into new Kconfig files in those directories
Port BSD tree.h header file
Add CONFIG_NET_ETHERNET (not used yet)
Notify upper layer when TIME_WAIT or FIN_WAIT2_2 timeout occurs
NET: Improvements to TCP connection fallback logic; Not needed with SO_LINGER.  From Max Holtzberg
Update ChangeLog
Fix error in tree.h