Making SimpleSinglePointerSelector warnings and errors easier to diagnose

By providing the "this" reference as the context object to Unity's Debug methods, when a message
comes up in the Unity Editor console window and the user clicks on it, the given game object will
be highlighted in the Hierarchy, making it easier to figure out which component is reporting the
issue.

Author: Robert El-Soudani

Assets/HoloToolkit/Input/Scripts/Focus/SimpleSinglePointerSelector.cs

@@ -55,7 +55,7 @@ private void Start()
             FindCursorIfNeeded();
             ConnectBestAvailablePointer();
 
-            Debug.Assert(currentPointer != null);
+            Debug.Assert(currentPointer != null, this);
         }
 
         private void OnEnable()
@@ -134,6 +134,7 @@ private void FindCursorIfNeeded()
             if ((Cursor == null) && SearchForCursorIfUnset)
             {
                 Debug.LogWarningFormat(
+                    this,
                     "Cursor hasn't been explicitly set on \"{0}.{1}\". We'll search for a cursor in the hierarchy, but"
                         + " that comes with a performance cost, so it would be best if you explicitly set the cursor.",
                     name,
@@ -144,11 +145,12 @@ private void FindCursorIfNeeded()
 
                 if ((foundCursors == null) || (foundCursors.Length == 0))
                 {
-                    Debug.LogErrorFormat("Couldn't find cursor for \"{0}.{1}\".", name, GetType().Name);
+                    Debug.LogErrorFormat(this, "Couldn't find cursor for \"{0}.{1}\".", name, GetType().Name);
                 }
                 else if (foundCursors.Length > 1)
                 {
                     Debug.LogErrorFormat(
+                        this,
                         "Found more than one ({0}) cursors for \"{1}.{2}\", so couldn't automatically set one.",
                         foundCursors.Length,
                         name,