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

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

I was myself a little confused when I saw `R` for a registered address,
since I interpreted it as "router" (though the node wasn't supposed to
be a router). After a wild goose chase for wrongly set flags through the
code I found that `R` stands for "REGISTERED". To prevent such a thing
in the future I opted for fixing this in the output.

examples: networking support for default example

boards/core: removed some hwtimer leftovers

Adds basic link layer functionality to the default example application.

gnrc_sixlowpan_nd: register new addresses for AAC