Wood Shader - Perlin Noise

I think I found the main problem of the wood shader, I had some big bugs in the Perlin noise. I don't remember where I got the original and what I did to transform it, but obviously I had programmed something which didn't have much to do with Perlin noise. It took some time to finally get it, that the implementation was completely useless and had to be thrown away. I started again and this time kept to a known good implementation. I think it looks much better.

So now I will do some more clean up and also add some more little features to the wood shader. And then it should finally work.