vtimer: fix callback usage

There is no need to test the "handler" set in the vtimer struct, and
have some code executed then. We just can make the code to execute the
handler. To lengthy `if else if`, just a call.
ccnl: fixed commenting style
ccnl: eliminated empty translation unit warning
make: removed shell_commands dependency
core/msg: revert part of #1285

use m->sender_pid instead of sched_active_pid again
undoes the optimization intended by #1285
fixes uint/int warning
boards/z1: fix cc2420_txrx function in CC2420 driver HAL

When waiting for transmission (to CC2420) to be done,
we were wrongly waiting for UCBUSY bit to be set,
while one should actually wait for that bit to be cleared.
core/msg: set m->sender_pid before it is used

fixes `msg_send_to_self` condition
SQUASHME: do it right
Merge pull request #1386 from haukepetersen/fix_shellcmd_dep

make: removed shell_commands dependency
destiny: deleting packed attribute from socket_internal_t

While testing the tcp implementation on MSBA2 I noticed that
the value of `tcp_input_buffer_end` gets changed whenever acquiring or
releasing the mutex of the struct on the server side.

After deleting the packed attribute of the struct this problem was
resolved and the value stayed the same after acquiring and releasing.

This problem could maybe arise from badly placed cache lines due to
missing padding... I am not sure.

Anyway, I guess using the packed attribute is useless here and makes it
more error-prone.
destiny: Adjust TCP_STACK_SIZE

Currently, the TCP_STACK_SIZE is `KERNEL_CONF_STACKSIZE_DEFAULT`.
However, since printf statements are used in the tcp relevant code,
this stack size is too small (esp. for MSBA2).
Merge pull request #1391 from cgundogan/fix_tcp_kernel_conf_stack_size

destiny: Adjust TCP_STACK_SIZE
Merge pull request #1390 from cgundogan/fix_socket_internal_t_packed_attr

destiny: deleting packed attribute from socket_internal_t
tests&examples: use sizeof(stack) in thread_create

fixes #1392
tests&examples: apply coding conventions to sizeof
test: remove superfluous stack size defines
Merge pull request #1388 from rousselk/fix-z1-cc2420-txrx

boards/z1: fix cc2420_txrx function in CC2420 driver HAL
Merge pull request #1393 from LudwigOrtmann/issue-1392

tests/examples cleanup
Add argument to thread_create
core: remove extra thread_create_arg() function