Do not trigger global repair when forwarding error is detected
Rank error packet should not be forwarded
Drop forwarding error packet and send back DAO to originating parent
Force NUD on default routers
uip-ds6-nbr: consider reachable node if LL-NUD

The reachable state might also be considered to keep the reachable
state since we are already not standard complaint. This reduces the
nbr discovery messages if nodes talk to each other periodically.
Merge pull request #652 from cetic/pr-rpl-rank-and-fw-errors

RPL rank and forward errors
Merge pull request #836 from lebrush/nbr-ll-nup

uip-ds6-nbr: consider reachable node if LL-NUD
Cleanup of the Contiki network layer configuration. Now using CONTIKI_WITH_IPV6, CONTIKI_WITH_IPV4, and CONTIKI_WITH_RIME in makefiles, and UIP_CONF_IPV6, UIP_CONF_IPV4, UIP_CONF_RIME in c code. Now only the stacks that are used are compiled (via makefile MODULES). Make IPv6 the default network stack.
Get IPv6 to fit in micaz platform again
Remove now unneeded UIP_CONF_IPV6 guards in net/ipv6 and net/rpl code
Cooja platform: do not include the rime module by default
Network layer configuration: replace UIP_CONF_* with NETSTACK_CONF_WITH_*
slip-radio: remove unneeded definition of NETSTACK_CONF_WITH_RPL (now set from makefile with CONTIKI_WITH_RPL)
WITH_UIP6 -> NETSTACK_CONF_WITH_IPV6
Remove unneeded module inclusion from avr and seedeye platforms