RIOT-OS/RIOT — pull request #397 by thomaseichinger (2013-12-03 12:13:10+00:00)
Title: enforce KERNEL_CONF_STACKSIZE_PRINTF in kernel.h

fixes issue https://github.com/RIOT-OS/RIOT/issues/266 by checking for ```KERNEL_CONF_STACKSIZE_PRINTF``` and raising an error if not defined.