Use REUSE framework

[nlohmann]

See https://reuse.software

• Added license headers to relevant source files.
• Added CI step to check REUSE compliance.

[coveralls]

Coverage remained the same at 100.0% when pulling 71aa668 on reuse into 2a9ae2b on develop.

[gregmarr]

Is it expected that the single include now has all the individual license blocks in it?

[nlohmann]

Is it expected that the single include now has all the individual license blocks in it?

I guess yes. It’s not nice, but accurate.

[gregmarr]

Is the removal of the license files from tools and tests/thirdparty expected? Are they located somewhere else now?

[falbrechtskirchinger]

They've all moved into the LICENSES/ folder, right?

[gregmarr]

Those files in LICENSES/ just look like templates, not specific licenses for specific files.

[falbrechtskirchinger]

This seems to be the way to handle this today. Keep the specific copyright information with SPDX identifier in the source and bundle the license "templates".

That's the idea I'm getting based on other projects' usage. anyway.

[gregmarr]

After digging further, it looks like the licenses are also in the source files in those directories, so no separate license file is needed.

[nlohmann]

The idea of REUSE is to make the project a bit more machine-readable. You can call pipx run reuse spdx to get a bill of materials that contains, for each file, the license and copyright.

I removed all license files from the project, because REUSE only requires one copy in the LICENSES folder for every used license - all things that would be filled in there are exactly the copyrights we have in the files. I kept the root LICENSE.MIT to help GitHub understand that the main part of the project is MIT-licensed. If I have to guess, GitHub will eventually also overwork their license support.