Switch from texture based color and radius to attribute based

[andeplane]

There is a significant performance hit when coloring atoms by property, and the reason for this is that colors currently are being set using textures which is slower than an attribute based coloring method. A caveat here is that since LAMMPS is reordering particle indices, we would have to either detect this, or set all colors every frame, both of which is expensive. Not sure what the best solution is.