Ward BRDF - 3

I only looked briefly into the problem I had when changing the model. I even found the reason it didn't work. In the process to locate the problem I checked the color component, as this was not exhibiting the same kind of problems. I found out that the reason is, that the color shaders are never destroyed, whereas the shader model is always deleted. The second is wrong (I need the objects around for undo/redo), so the reason it stopped was only an indication of something else being wrong. I fixed the root cause for the assert which fired (so the GL-representation can now be deleted successfully when the object is no longer needed), but the code still has a bug (it deletes the object too early).