This is an intermediate steps towards making lights actual geometry.
Light is now a subclass of Geometry, which simplifies some code.
The geometry is not added to the BVH yet, which would be the next
step and improve light intersection performance with many lights.
This makes object attributes work on lights.
Co-authored-by: Lukas Stockner <lukas@lukasstockner.de>
Pull Request: https://projects.blender.org/blender/blender/pulls/134846
Plotting happens from the given root node into a graphviz file.
Supports plotting from both scene level LightTreeNode and the kernel
level KernelLightTreeNode.
An external graphviz command is to be used to convert generated file
to an image.
Pull Request: https://projects.blender.org/blender/blender/pulls/134738
