Copy SEGGER JLink scripts from boards/openmote to boards/cc2538dk.
boards/cc2538dk: Support flashing and debugging using the SEGGER JLink.
core: refactor sched_run

`sched_run()` was cluttered. Many individual changes were done without a
proper refactoring.
Merge pull request #1841 from Kijewski/sched_yield-result

 core: refactor sched_run
config: use radio_address_t
config: moved from core to sys

There's no need to run config_load from core directly, can be done by
auto_init.
config: make members feature specific

Channel and address are only sensible for boards that actually have a
transceiver.
config: suppress cppcheck warnings
Merge pull request #1909 from locicontrols/cc2538dk-jlink

boards/cc2538dk: Support flashing and debugging using the SEGGER JLink.
Merge pull request #1900 from OlegHahm/config_radio_address_t

config: use radio_address_t in config_t
drivers/at86rf231: refactoring of the at86rf231 radio driver

* deploy extended operation mode
* cleanup
* implement netdev 802154.h interface
netdev/802154: suppress cppcheck warnings in 802154.h

Suppress cppcheck warnings of class unusedStructMember because
this interface is not used yet. Remove these comments once it
is used.