use quaternions instead of MRPs

also use correct time propagation equation
disable the fused sensors when gyro is not present since
they were unusable in practice.

Change-Id: Iad797425784e67dc6c5690e97c71c583418cc5b5
diff --git a/services/sensorservice/CorrectedGyroSensor.cpp b/services/sensorservice/CorrectedGyroSensor.cpp
index 9b75b70..1857443 100644
--- a/services/sensorservice/CorrectedGyroSensor.cpp
+++ b/services/sensorservice/CorrectedGyroSensor.cpp
@@ -45,7 +45,7 @@
         const sensors_event_t& event)
 {
     if (event.type == SENSOR_TYPE_GYROSCOPE) {
-        const vec3_t bias(mSensorFusion.getGyroBias() * mSensorFusion.getEstimatedRate());
+        const vec3_t bias(mSensorFusion.getGyroBias());
         *outEvent = event;
         outEvent->data[0] -= bias.x;
         outEvent->data[1] -= bias.y;