During the development of the new nodes in the `geometry-nodes` branch the color of the new nodes wasn't considered, so all of the nodes ended up red, the color for "input" nodes. This patch introduces two new colors, one for "Geometry" and one for "Attributes". There are only two attribute nodes currently, but the next sprint will add two more, attribute mix, and sample from texture. The attribute nodes are conceptually different enough from the nodes that modify the geometry that they deserve their own color. Differential Revision: https://developer.blender.org/D9682