Added GLTF submodule and start of ModelLoader

Sandbox/content/Shaders/testShader.hlsl

@@ -0,0 +1,54 @@
+cbuffer SceneConstants
+{
+    float4x4 ViewProjection = float4x4(1, 0, 0, 0, 
+        0, 1, 0, 0, 
+        0, 0, 1, 0, 
+        0, 0, 0, 1);
+}
+
+cbuffer ObjectConstants
+{
+    float4x4 Transform;
+}
+
+cbuffer Constants
+{
+    float4 BaseColor;
+    float3 LightDir;
+}
+
+struct VS_IN
+{
+    float3 Position : POSITION;
+    float3 Normal   : NORMAL;
+};
+
+struct PS_IN
+{
+    float4 Position : SV_POSITION;
+    float3 Normal   : NORMAL;
+};
+
+PS_IN VS(VS_IN input)
+{
+    PS_IN output;
+	
+	float4 worldPosition = mul(Transform, float4(input.Position, 1));
+	
+    output.Position = mul(ViewProjection, worldPosition);
+    output.Normal = mul((float3x3)Transform, input.Normal);
+    
+    return output;
+}
+
+float4 PS(PS_IN input) : SV_TARGET
+{
+    input.Normal = normalize(input.Normal);
+
+    float shading = dot(LightDir, input.Normal);
+    shading = clamp(shading, 0.0f, 1.0f);
+
+    return BaseColor * shading;
+}
+
+#effect[VS=VS,PS=PS]