Merge pull request #6156 from keestux/add-driver-bme280

drivers/Makefile.dep

drivers/Makefile.include

drivers/bme280/Makefile

drivers/bme280/bme280.c

drivers/bme280/bme280_saul.c

drivers/bme280/include/bme280_internals.h

drivers/bme280/include/bme280_params.h

drivers/include/bme280.h

sys/auto_init/auto_init.c

sys/auto_init/saul/auto_init_bme280.c

tests/driver_bme280/Makefile

tests/driver_bme280/Readme.md

tests/driver_bme280/main.c