Merge pull request #1836 from Kijewski/yield-less

core/include/arch/thread_arch.h

core/include/sched.h

core/include/thread.h

core/msg.c

core/mutex.c

core/sched.c

core/thread.c

cpu/arm_common/arm_cpu.c

cpu/lpc1768/atom.c

cpu/lpc1768/include/cpu.h

cpu/msp430-common/cpu.c

cpu/native/native_cpu.c

cpu/x86/x86_interrupts.c

cpu/x86/x86_threading.c

sys/pipe/pipe.c

sys/posix/semaphore.c

tests/sched_testing/Makefile

tests/sched_testing/main.c