Update for procedural pine tree

The Update Version 1.1 fixes a few bugs in the LOD system and comes with a sharper mipmapping for the pine leaf texture (compare screenshots, those without the number of triangles rendered in the top left corner are the new ones). Also, fading in masked textures by using mesh alpha causes a pop-in artefact when going from 0.99999 to 1.0, an issue that needs a fix.