Added shaders for deferred shadow example

data/shaders/deferredshadows/shadow.vert

@@ -0,0 +1,19 @@
+#version 450
+
+#extension GL_ARB_separate_shader_objects : enable
+#extension GL_ARB_shading_language_420pack : enable
+
+layout (location = 0) in vec4 inPos;
+
+layout (location = 0) out int outInstanceIndex;
+
+out gl_PerVertex 
+{
+	vec4 gl_Position;   
+};
+
+void main()
+{
+	outInstanceIndex = gl_InstanceIndex;
+	gl_Position = inPos;
+}