Add size for R8G8B8A8_UInt DXGI format to managed code

Author: jmquigs

MMManaged/MeshUtil.fs

@@ -508,6 +508,7 @@ map_Kd $$filename
                 | SharpDX.DXGI.Format.R32G32B32A32_Float -> 16
                 | SharpDX.DXGI.Format.R16G16_Float -> 4
                 | SharpDX.DXGI.Format.R16G16B16A16_Float -> 8
+                | SharpDX.DXGI.Format.R8G8B8A8_UInt -> 4
                 | _ -> failwithf "Some lazy person didn't fill in the size of type %A" f
         int hElement.Offset + sizeBytes