batman-adv: Distributed ARP Table - create DHT helper functions

Add all the relevant functions in order to manage a Distributed Hash Table over
the B.A.T.M.A.N.-adv network. It will later be used to store several ARP entries
and implement DAT (Distributed ARP Table)

Signed-off-by: Antonio Quartulli <ordex@autistici.org>

diff --cc net/batman-adv/Makefile
Simple merge

diff --cc net/batman-adv/distributed-arp-table.c
Simple merge

diff --cc net/batman-adv/distributed-arp-table.h
Simple merge

diff --cc net/batman-adv/hard-interface.c
Simple merge

diff --cc net/batman-adv/main.h
Simple merge

diff --cc net/batman-adv/originator.c
Simple merge

diff --cc net/batman-adv/types.h
Simple merge

diff --cc net/batman-adv/unicast.c
Simple merge

diff --cc net/batman-adv/unicast.h
Simple merge