Do not zero out sched_threads needlessly

The function sched_init() zeroes out sched_threads needlessly. All
static variables can be assumed to be initialized with zero, anyways.
The C standard mandates it, and all at other places in the code it is
assumed.
Add a reboot() function to kernel.h definitions.
Implemented reboot() function for MSP430 MCUs
Add wireshark dissector for native packets
core: msg: don't wake up sender after receive if it's REPLY_BLOCKED

solves issue #100

If the sender is reply-blocked, waking it up after its message has been
delivered is wrong. It needs to stay reply-blocked until the reply has
been delivered.
core: msg: add some debug statements
core: msg: yield after queueing of a message if REPLY_BLOCKED

When setting the running task reply_blocked, it is implicitly removed
from the runqueue. But if queueing of a msg is actually successful, the
thread exits msg_send without yielding, continuing to run even if it's
not supposed to.

Nice example of why multiple function exit points lead to weird
errors...
Use `filter` instead of `findstring`

See #672
Function attributes are now defined elsewhere ("attributes.h")
Implemented reboot() function for ARM-based MCUs
Added while(1) to ensure GCC valids NORETURN; fixed indentation
Eliminate findstring in more places
https://github.com/Kijewski/RIOT/commit/102dc453828012985f82915ad826be069f444e61#commitcomment-5378590
implement rudimentary native reboot
Added while(1) to ensure GCC valids NORETURN; fixed indentation
Merge pull request #1 from LudwigOrtmann/native_reboot

implement rudimentary native reboot
add system calls to the shell
Merge pull request #2 from LudwigOrtmann/shell_syscalls

add system calls to the shell (to implement a reboot command)
use filter instead of findstring in BOARD_BLACKLIST checking
fix ignore_add unused parameter warning