septernion: Correct quaternion normalization after averaging

Resolves bug-report http://bugs.openfoam.org/view.php?id=2203

src/OpenFOAM/primitives/septernion/septernion.C

@@ -93,7 +93,7 @@ Foam::septernion Foam::average
         }
     }
 
-    normalize(sa.r());
+    sa.r().normalize();
 
     return sa;
 }