* Replace license text in headers with SPDX identifiers.
* Remove specific license info from outdated readme.txt, instead leave details
to the source files.
* Add list of SPDX license identifiers used, and corresponding license texts.
* Update copyright dates while we're at it.
Ref D14069, T95597
When rendering volume surfaces in unbounded worlds the volume stepping can produce large values. If used with a magic texture node the values can results in a Inf float which when used in a sin or cos produces a NaN.
To fix this the input values are mapped into the periodic range of the sin and cos functions (-2*PI 2*PI) this stops the possibility of a Inf occurring and thus the NaN. It also improves the accuracy and smoothness of the result due to loss of precision when large values are summed with smaller ones effectively removing the parts of the smaller number (i.e. those in the -2PI to 2PI range) that result in variation of the output of sin and cos.
Reviewed By: brecht
Maniphest Tasks: T92036
Differential Revision: https://developer.blender.org/D12821
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.
