Temporary workaround
Upgrade FreeRTOS to v8.1.2 for event_groups support.
Add math library for future use
Sensor: Refactor the read task with event_group, WIP.
Merge branch 'TEMP_SENSOR' into GY-801-sensor

Refactoring is not completed, will not work.

Conflicts:
	inc/sensor/hmc5883l.h