Completed CC2420 constants documentation (DOxygen)
examples/hello-world: return instead of busy loop.
Merge pull request #973 from LudwigOrtmann/examples_hello-world_update

examples/hello-world: return instead of busy loop.
posix: Add pthread_cleanup handlers

With `pthread_cleanup_(push|pop)` you can define a function that should
be ran if the thread is exited while it is inside this scope. A thread
can be ended here through an explicit call to `pthread_exit()`, or if
cancellation was requested and a cancellation point was hit.

`pthread_cleanup_*` is mostly only useful together with cancellation
points, and cancellation points are only useful with a cleanup
functionality. Cancellation points are at least partially implemented by
means of `pthread_testcancel()`.

C.f. ["Cancellation Points"][1].

  [1]: http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html#tag_15_09_05_02
pthread_cleanup: better documentation
pthread_cleanup: fixup for #798
Merge pull request #789 from LudwigOrtmann/native_gprof

native profiling tools support
Fix dereferencing of type-punned pointer

Fixes #897
Add `pthread_barrier_*` functions

Compare [`pthread_barrier_init`][1].

  [1]: http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_barrier_init.html
Add pthread_barrier test
Add pthread_barrier_t documentation
Clean up test_irq (fix #943)
make: replace findstring with filter in sys/Makefile
gitignore cachegrind.out
Merge pull request #988 from Kijewski/ignore-cachegrind.out

gitignore: add cachegrind.out
Merge pull request #778 from LudwigOrtmann/dependency_files

Make: Prepend path to dependency info files with sed
Merge pull request #914 from authmillenon/fix-dereferencing

net: sixlowpan: Fix dereferencing of type-punned pointer
Merge pull request #813 from Kijewski/add-pthread_barrier

posix: Add `pthread_barrier_*` functions
Merge pull request #986 from Kijewski/a-minor-fix-for-issue-672-not-everything-but-better-than-nothing-i-guess-or-what-do-you-think

make: replace findstring with filter in sys/Makefile
Merge pull request #821 from Kijewski/pthrad_cleanup

posix: Add pthread_cleanup handlers