cpu/stm32f0: fixed hardfault indication
prevent rounding 0 if HWTIMER_SPEED > 1000000L

The current macros in hwtimer.h expect HWTIMER_SPEED to be < 1000000L, otherwise integer arithmetic will round the result down to 0.
Add a case to prevent that.
cpu/stm32f4 changed SPI-return values to API defs
sys/transceiver: cc2420 handles 802.15.4 packets
shell/transceiver: properly initialize 802.15.4 packet
core: moved `#include`s outside the `extern "C"` guards
drivers: add `extern "C"` to header files
make: initialize debugger with TERMFLAGS
ip: set solicited node address correctly
Merge pull request #1805 from BytesGalore/extern_C_in_headers_core_unguard_includes

core: moved `#include`s outside the `extern "C"` guards
Merge pull request #1807 from BytesGalore/extern_C_in_headers_drivers

drivers: add `extern "C"` to header files
added missing `extern "C"` guards
Merge pull request #1853 from authmillenon/solicited-node-address-fix

ip: set solicited node address correctly
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