conn: Initial import of a light-weight network application API

examples: unblacklist boards in gnrc_networking

xtimer: initialize struct members

6lowpan nd: check right NCE in AR handling

When checking the address registration option, the address has to be passed in order to check the correct neighbor cache entry.

cpu/kinetis_common: periph/timer, read PIT value before stopping

6lbr: initialize router advertisement intervals

atmega: added panic function

ATmega now has a panic function, no need for blacklisting any more.

gnrc_sixlowpan_nd_router: cast before shifting

all: Update @gebart family name, email

6lowpan nd: send router advertisements on 6LR

examples: provide example application for a 6LoWPAN border router

A router should turn into a router after receiving a valid router advertisement.

`avr-gcc` was complaining about shifting the value out of the width of
type. This is a fix for that.

core: replace and remove DEBUGF macro and replace __FILE__ by RIOT_FILE_RELATIVE

The xtimer_t struct members target and long_target are used in _is_set() function in xtimer_remove(), but will be uninitialized.

example: disable gnrc modules without netif

examples/default: fix indentation in Makefile

gnrc_sixlowpan_nd: activate NC state machine

tests: added test for periph_timer plus adaption

sc_ipv6_nc: Use more letters for type