Slightly reworked glTF samples

Parent matrices are now applied (where available)
Now more in line with the base code glTF loader
Refs #964

data/shaders/hlsl/gltfloading/mesh.frag

@@ -24,7 +24,7 @@ float4 main(VSOutput input) : SV_TARGET
 	float3 N = normalize(input.Normal);
 	float3 L = normalize(input.LightVec);
 	float3 V = normalize(input.ViewVec);
-	float3 R = reflect(-L, N);
+	float3 R = reflect(L, N);
 	float3 diffuse = max(dot(N, L), 0.0) * input.Color;
 	float3 specular = pow(max(dot(R, V), 0.0), 16.0) * float3(0.75, 0.75, 0.75);
 	return float4(diffuse * color.rgb + specular, 1.0);