sys/transceiver: cc2420 handles 802.15.4 packets
shell/transceiver: properly initialize 802.15.4 packet
make: initialize debugger with TERMFLAGS
added missing `extern "C"` guards
core: msg: introduce msg_try_send
core: adapt to msg_try_send
Merge pull request #1847 from kaspar030/msg_try_send

core: introduce msg_try_send
 core: make sched_runqueues static

 PR #1000 overlooked to rename `runqueues` into `sched_runqueues` in
 `sched.h`. This shows that the variable is not used outside of
 `sched.c`.

 As the list should not be accessed outside of the scheduler, so it
 can be `static`.
sys: lib: ringbuffer: introduce ringbuffer_get_free

This function returns the number of bytes available in the ringbuffer.
Merge pull request #1650 from kaspar030/ringbuffer_get_free

sys: lib: ringbuffer: introduce ringbuffer_get_free
dist: add Dockerfile for docker builder container
Merge pull request #1637 from kaspar030/docker

dist: add Dockerfile for docker builder container
Merge pull request #1816 from Kijewski/runqueues-name-fixup

 core: make sched_runqueues static
make: doc: clean up dist Makefile
Merge pull request #1858 from OlegHahm/dist_makefile

make: doc: clean up dist Makefile
Merge pull request #1851 from authmillenon/native-debug-args

make: initialize debugger with TERMFLAGS
Merge pull request #1856 from BytesGalore/extern_C_in_headers_drivers_add_new_headers

drivers: added missing `extern "C"` guards in new files
cpu: use typed function pointer for thread_arch_init
Merge pull request #1866 from OlegHahm/core_fix_thread_init_prototype

cpu: use typed function pointer for thread_arch_init
cppcheck: don't needlessly assign sched_active_pid