Dev/defininitions (#262)

* Added CardinalAxis and FlattenMode enum definitions

* removes specific language to bounding box

* Fixed cardinal axis offset. (should be power of 2 ie: 1,2,4,8,16...)

XRTK-Core/Packages/com.xrtk.core/Definitions/Utilities/CardinalAxis.cs

@@ -17,6 +17,6 @@ public enum CardinalAxis
         // None = 0,
         X = 1,
         Y = 2,
-        Z = 3,
+        Z = 4,
     }
 }