moved debugging statements from header to c file

Additionally, declaring the stacks as static.
amendment - to be squashed
tests: add test that shows sequence of received messages
test_thread_msg_seq: add missing main() return statement
core:mutex: allow idle thread to use mutexes
Add test if the message queue is fair
use cpu dependent stack size
use forwarding table entry when routing

So far the entry was looked up, but ignored in the case where the packet
has to be forwarded.
added missing hdr position shift
Change reboot signature.

Change from `void reboot(void)` to `int reboot(int mode)`.
Move reboot definition to core, rename architecture implementations
from reboot to reboot_arch.
Declare reboot mode(s) in kernel.h, reboot_arch in kernel_internal.h
Currently only one reboot mode is handled, its use is enforced.

Rationale:
A reboot function is already defined in <unistd.h> on BSD systems.
(See: http://www.openbsd.org/cgi-bin/man.cgi?query=reboot&sektion=2)
This patch not only allows native to build sensibly on these systems
but also streamlines RIOTs compatability with existing software.
shell: accept UTF8 input
shell: don't ignore IO errors
shell: add myself to authors
notify lowpan_transfer when IP packet is not routable

The IP process silently discarded an unroutable packet without replying to the 6LoWPAN layer, causing that thread to starve.
Ensure that stack pointer is correctly aligned during thread creation on MSP430
Merge pull request #878 from OlegHahm/unroutable

net: sixlowpan: notify lowpan_transfer when IP packet is not routable
make/buildtest: print errors

Display all stderr output but suppress warnings.

implements https://github.com/RIOT-OS/RIOT/issues/835
Merge pull request #822 from LudwigOrtmann/reboot_signature

core: change reboot signature.
ipc_pingpong: start receiving thread immediately

Rationale: When using `msg_send_receive()` the receiving thread needs to
be already in receiving mode.
posix: move posix semaphore in posix module