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/vec.h b/services/sensorservice/vec.h
index 736ff37..f74ccc5 100644
--- a/services/sensorservice/vec.h
+++ b/services/sensorservice/vec.h
@@ -208,6 +208,15 @@
 }
 
 template <
+    template<typename T, size_t S> class V,
+    typename TYPE,
+    size_t SIZE
+>
+V<TYPE, SIZE> PURE normalize(const V<TYPE, SIZE>& v) {
+    return v * (1/length(v));
+}
+
+template <
     template<typename T, size_t S> class VLHS,
     template<typename T, size_t S> class VRHS,
     typename TYPE