native cpu initial import

core/include/kernel_intern.h

core/thread.c

cpu/makefile

cpu/native/atomic_cpu.c

cpu/native/hwtimer_cpu.c

cpu/native/include/cpu-conf.h

cpu/native/include/cpu.h

cpu/native/include/hwtimer_cpu.h

cpu/native/irq_cpu.c

cpu/native/lpm_cpu.c

cpu/native/makefile

cpu/native/native_cpu.c

cpu/native/rtc/makefile

cpu/native/rtc/posix-rtc.c

cpu/native/startup.c

makefile.base