Replace '-' with '_' in BOARD and CPU_… macros
Fix BOARD macro
removing possible invalid check

Checking for a link local address to determine if a node is on-link is
probably not a valid assumption in most wireless networks.
native: don't use RIOT read/write in UART
Prepend path to dependency info files with sed

The old way was error prone due to it's use of a fixed path file and
confusing.

closes #775
pipe through sed instead

addresses: https://github.com/RIOT-OS/RIOT/pull/778#discussion_r10041955
change new/overlooked Makefiles
remove some newlines
examples/rpl_udp: use defaulttransceiver
Added standard way to query CCA status on CC2420 transceiver (squashed)
Completed CC2420 constants documentation (DOxygen)
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
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