abc: rename method to match linklayer-only functionality
abc-iface: change title comment
abc-iface: allow ptr for additional private data
abc-ip: check if interface is enabled
abc-ip: return 0 in set_enable callback since we can't change it
abc-ip: change comment to reflect always-on nature of an abc-ip iface
abc-ip: remove info print (debug)
abc: allow individual sockaddr types in each driver

Needs next commit for abc-ip to work
abc-ip: use UDP packets instead of raw socket

Removes setuid 0 restriction
Might make abc-ip work on OS X
Uses UDP port 43969
pqueue: add info about not being thread safe
pqueue: fix make_room to not delete messages with higher priority

Old code would only check last element against the new priority
Also, make_room is now non-destructive when not enough room
pqueue: printf and documentation update
pqueue: queue_add now returns success value
pqueue: extra semicolon fixup
pqueue: add backoff test case, update documentation
abc: documentation update about what drivers requires root
abc: unamanged: only forward new messages instantly
abc: dont incremented backoff on send errors
abc: log error when queue is full
abc: only increment cycle counter when data was sent

Otherwise backed off messages are not guaranteed to
be sent the number of times wanted before dropping out.