normalize quaternion.Slerp outputs

OpenSim/Region/Framework/Scenes/KeyframeMotion.cs

@@ -575,6 +575,7 @@ namespace OpenSim.Region.Framework.Scenes
                             Quaternion current = m_group.GroupRotation;
 
                             Quaternion step = Quaternion.Slerp(m_currentFrame.StartRotation, (Quaternion)m_currentFrame.Rotation, complete);
+                            step.Normalize();
 /* use simpler change detection
  * float angle = 0;
 

OpenSim/Region/Framework/Scenes/SceneObjectPart.cs

@@ -5202,6 +5202,7 @@ namespace OpenSim.Region.Framework.Scenes
                     }
 
                     Quaternion rot = Quaternion.Slerp(RotationOffset,APIDTarget,1.0f/(float)m_APIDIterations);
+                    rot.Normalize();
                     UpdateRotation(rot);
 
                     m_APIDIterations--;