CellSizeDivider

The CellSizeDivider does not seem to work as intended with SimpleMaterial. I had to use a CellCountdivider (I noticed they used that as well in the unittests). It seems the issue is that CellSizeDivider requires a material to be set, but does not expose a property or method to set it.

I would think, from a design perspective, that the cellsizedivider would take on the texture of the material it gets bound to. Nonethless, just a minor bug, since CellCountDivider works. Just a heads up.