Merge pull request #6398 from phectori/maple-mini

boards/maple-mini/Makefile

boards/maple-mini/Makefile.features

boards/maple-mini/Makefile.include

boards/maple-mini/board.c

boards/maple-mini/dist/openocd.cfg

boards/maple-mini/include/board.h

boards/maple-mini/include/gpio_params.h

boards/maple-mini/include/periph_conf.h

examples/dtls-echo/Makefile

examples/gnrc_border_router/Makefile

tests/gnrc_ipv6_ext/Makefile

tests/gnrc_sixlowpan/Makefile

tests/mpu_stack_guard/Makefile

tests/pkg_cmsis-dsp/Makefile

tests/thread_cooperation/Makefile

tests/unittests/Makefile