* In a previous update in 2021 many copyright ranges were truncated
accidentally, and some files have been copy-pasted with wrong years. These
dates have been fixed based on git history and original copyright messages.
* It's not particularly scalable and can be brittle to driver changes, and we
can use targeted specific pixel tests to check what we really want - to see if
the output has rendered correctly.
* Overlay tests still check files directly - this is a future refactor to
remove.