Adds scrambling distance to the PMJ sampler. This is based
on the work by Mathieu Menuet in D12318 who created the original
implementation for the Sobol sampler.
Reviewed By: brecht
Maniphest Tasks: T92181
Differential Revision: https://developer.blender.org/D12854
Remove prefix of filenames that is the same as the folder name. This used
to help when #includes were using individual files, but now they are always
relative to the cycles root directory and so the prefixes are redundant.
For patches and branches, git merge and rebase should be able to detect the
renames and move over code to the right file.