QRotationSensor and QCompass must provide more accurate values when assisted with gyro

QRotationSensor:when orientation of the device is got more accurately, heading, pitch and roll values are more accurate, too
QCompass: Gyro assisted values in fast movements give more stable and accurate values, more

TODO: To decide how gyro will be controlled to reduce power consumption
1.) No control: Always on, when gyro assisted sensors are used, alwaysOn can be controlled with policies
2.) To be triggered by the user, e.g.
a.) With a dedicated gesture
b.) "big-8" used with calibration/ shake
c.) With voice command
d.) With HW button e.g. display on, or any other
3.) To be controlled by the app, a flag:
a.) gyro on/off is controlled by the app, e.g.
QRotationSensor::setGyroAssistance(bool gyroAssisted);
b.) QRotationSensor::setHighAccuracyMode(bool highAccuracy);