Oculus VR DK2 Support

- Updated to work with 0.5.x SDK
- Uses Oculus Rendering rather than PostFX
- Stereo rendering refactored so more rendering info is grabbed from the DisplayDevice
- Implements an Offscreen Canvas for in-game gui with oculus
- Message dialogs and metrics display can now go to the OffScreen Canvas (if oculus demo is setup correctly)

Engine/source/math/util/frustum.h

@@ -53,6 +53,14 @@
 
 class OrientedBox3F;
 
+/// Advanced fov specification for oculus
+struct FovPort
+{
+   float upTan;
+   float downTan;
+   float leftTan;
+   float rightTan;
+};
 
 /// Polyhedron data for use by frustums.  Uses fixed-size vectors
 /// and a static vector for the edge list as that never changes