changed parameters form `kernel_pid_t` to `int`
fix license headers in non-.c files
tests: let license checker check cpp files, too
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
unittests: Fix coding conventions
Merge pull request #1615 from authmillenon/cbor-unittests-warnings

Fix unittests warnings
Merge pull request #1599 from LudwigOrtmann/issue-1597

sys/cbor,tests: fix cbor daylight saving time
tests: nativenet: Add return for radio thread
tests: nativenet: Add README.md
Fix comments
unittests: Simplify module-wise rebuild
Merge pull request #1612 from authmillenon/tests_nativenet_expect

tests: Add expect script for nativenet tests