drivers/at86rf231: fix two cppcheck findings
Merge pull request #1920 from thomaseichinger/at86_fix

drivers/at86rf231: fix two cppcheck findings
added spark core board
auto_init: adapt auto_init for cc110x devices
rpl_udp: Addresses must only be 8-bit with cc110x
rpl_udp: optimize error handling for set command
OSX: fix readlink call
Merge pull request #1728 from mehlis/add_board_spark_core

added spark core board
Merge pull request #1878 from authmillenon/rpl_udp-16bit-addr

rpl_udp: Addresses must only be 8-bit with cc110x
Merge pull request #1926 from mehlis/fix-readlink

OSX: fix readlink call
netdev: clarify documentation of netdev_driver_t::get_option()
Merge pull request #1928 from authmillenon/netdev-fix-doc

netdev: clarify documentation of netdev_driver_t::get_option()
cpu/cc2538: Enable the CC2538's more compact alternate interrupt mapping.
cc2538: reimplement the hwtimer module using the MCU's Sleep Timer which, unlike the GPTimers, will work in low-power modes PM1 and PM2.