Implement Level of Detail Scheme

[CaffeineViking]

Now that each individual component "works" we want to dynamically change between the maxified (strand-based) and the minified (volume-based) solutions "smoothly". Since we'll most likely only have 1-2 hair styles on the screen using the maxified case (relatively expensive because of the rasterization), we want to use our minified-case as much as possible, so our solution can scale nicely in the quality / performance space. For the minified-case we'll probably reduce the voxelization size (which reduces the number of raycasts needed since the step size will be shorter) and apply #41. When we are in the maxified-case we want to use our metric for hair density to blend less fragments in areas of high-density (since they'll have stuff there anyway), that can also be seen as a sort of LoD I guess. We also need to blend between the minified and maxified case, when the transition happens. If our minified case is really good then that might already be OK, but otherwise we can use dithering / blending. Finally, we need a good function metric to when these changes should happen.