Rewrite links to be serialized in uploaded textures

[jonobr1]

Right now the texture for all links is a flat list showing all nodes connected to all other nodes. The problem is that for any given node there needs to be traversal of the entire texture to look up its links.

This would be much more efficient if an index and length attribute were added to each node and that were applied to the uploaded texture. Then, a small portion of the links texture would need to be read on the GPU every frame greatly reducing the load (unless of course everything was connected to everything else; though in this scenario the current model would be just as slow).