changed parameters form `kernel_pid_t` to `int`
native: add stack smashing protection

When `DEVELHELP` is defined, add `-fstack-protector-all`.
board/pca1000[0|5]: enabled RNG peripheral
cpu/nrf51822: added RNG driver
fix license headers in non-.c files
tests: let license checker check cpp files, too
Merge pull request #1570 from LudwigOrtmann/native-ssp

native: add stack smashing protection
cpu/stm32f4: added random number generator driver
board/stm32f4discovery: enabled RNG driver
Merge pull request #1611 from haukepetersen/add_stm32f4_random

cpu/stm32f4: added random number generator driver
Merge pull request #1607 from haukepetersen/add_nrf_random

cpu/nrf51822: added random number generator driver
dist/tools: add cppcheck script

enables easy linting of the whole tree or just one branches changes against
another
tests: Add expect script for nativenet tests
Merge pull request #1608 from LudwigOrtmann/fixmorelicenseheaders

Fix more license headers
tests: fix lifo unittest

The API was violated resulting in an array overrun.
Merge pull request #1614 from LudwigOrtmann/unittests_fix

tests: fix lifo unittest
sys/cbor: set isdst to undefined after strptime

CBOR does not specify the daylight saving time adjustment.
tests: fix cbor unittest

Some member of `struct tm val` were not set, resulting in undefined
behavior.
unittests: Fix -Waddress warnings
unittests: Fix -Wunused-parameter warnings