More work on interface callbacks.

Author: rpavlik

OSVR-Unity/Assets/OSVRUnity/src/InterfaceCallbacks.cs

@@ -32,15 +32,31 @@ public class InterfaceCallbacks : MonoBehaviour
             public delegate void AnalogCallback(string source, float value);
             #endregion
 
-            void Start()
+            #region Event methods
+            public void Start()
             {
                 if (null == iface)
                 {
                     iface = OSVR.Unity.ClientKit.instance.context.getInterface(path);
                 }
             }
 
-            void OnDestroy()
+            public void OnDestroy()
+            {
+                Stop();
+            }
+
+            public void OnApplicationQuit()
+            {
+                Stop();
+            }
+
+            #endregion
+
+            /// <summary>
+            /// Used in the end-of-life method, this can also be called manually to free the internal interface.
+            /// </summary>
+            public void Stop()
             {
                 iface = null;
             }