Fixed dot error on RGBtoLuminance

MaterialGraphProject/Assets/Matt/RGBtoLuminance.cs

 
 		protected override MaterialSlot GetOutputSlot ()
 		{
-			return new MaterialSlot (OutputSlotId, GetOutputSlotName (), kOutputSlotShaderName, SlotType.Output, SlotValueType.Vector3, Vector4.zero);
 		}
 
         // Convert rgb to luminance with rgb in linear space with sRGB primaries and D65 white point (from PostProcessing)