Added SurfaceObserver property to spatial mapping manager

Author: Sacristan

Assets/HoloToolkit/SpatialMapping/Scripts/SpatialMappingManager.cs

@@ -47,6 +47,11 @@ public partial class SpatialMappingManager : Singleton<SpatialMappingManager>
         [HideInInspector]
         public float StartTime { get; private set; }
 
+        /// <summary>
+        /// SurfaceMappingObserver GET
+        /// </summary>
+        public SpatialMappingObserver SurfaceObserver { get { return surfaceObserver; } }
+
         /// <summary>
         /// The current source of spatial mapping data.
         /// </summary>