Fixes several files incorrectly stated a different license from the actual project, as well as the copyright headers included in all files. This change has no effect on the licensing terms, it should clear up a bit of confusion by contributors. Plus the files get a bit smaller, and we have less duplicated information across the entire project.
Overall the project is GPLv2 if not built with Qt, and GPLv3 if it is built with Qt. There are no parts licensed under a different license, all have been adapted from other compatible licenses into GPLv2 or GPLv3.
There is hardly any reason for us to recalculate everything all the time. LUTs can cache the work once, and then re-use it every time necessary, drastically reducing the impact of Color Grading by almost 60% (on some GPUs even more). Additionally this fixes the negative gamma issue, which plagued the filter for a while.
In the future, once PR 4199 (https://github.com/obsproject/obs-studio/pull/4199) has been merged, we can cut away one intermediate rendering step currently required to make the effect work. Hopefully this will be with the 27.x release of OBS Studio.
