Shading: Add White Noise node.

The White Noise node hashes the input and returns a random number in the
range [0, 1]. The input can be a 1D, 2D, 3D, or a 4D vector.

Reviewers: brecht, JacquesLucke

Differential Revision: https://developer.blender.org/D5550

release/scripts/startup/nodeitems_builtins.py

@@ -237,6 +237,7 @@ shader_node_categories = [
         NodeItem("ShaderNodeTexBrick"),
         NodeItem("ShaderNodeTexPointDensity"),
         NodeItem("ShaderNodeTexIES"),
+        NodeItem("ShaderNodeTexWhiteNoise"),
     ]),
     ShaderNodeCategory("SH_NEW_OP_COLOR", "Color", items=[
         NodeItem("ShaderNodeMixRGB"),