Add SPDX header

[AndyScherzinger]

• replacing former license headers with standardized and unified SPDX headers
• adding a GH action to check any future PRs for compliance
• unified header => move any author to the newly added AUTHORS.md
• Add Badge to the readme reflecting the current compliance status of the main branch

[AndyScherzinger]

@dartcafe as mentioned the last days on the chat, here is the PR moving things to standardized SPDX headers - looking forward to your feedback as well @v1r0x

[AndyScherzinger]

Since the questions came up on the use of a generic spdx header:

• https://reuse.software/faq/#many-copyright-statements
• https://reuse.software/faq/#when-copyright

In essence: many people when having been asked how to deal with adding such headers voted in favor of the generic solution and an authors-list file. So PRs aren't polluted with header changes and folks aren't sending PRs which just change dates on copyright headers because it is a new year.

[dartcafe]

Fine for me.

[dartcafe]

Sorry to interrupt
Ist it possible to keep the first Autor aka copyright holder and the initial publishing date?

[AndyScherzinger]

@dartcafe can you clarify a bit more?

To comment on your request:

• all files should have a date and that date should always be the year of the initial commit of that file
• the first author is not the copyright holder, all authors are, so while one could add the first committer with an explicit copyright line, all other contributors also have a copyright. The same way the initial author has -> to the lines of code they contributed to that specific file. Hence I would argue to not add the first committer explicitely

[dartcafe]

My point was just to respect the historical usage of the copyright entry. For me personally it is not important.
Thanks for the explanation.

[dartcafe]

@v1r0x Do you have any comment for this change? Otherwise I would ask @AndyScherzinger for merging this PR.

[AndyScherzinger]

Rebased and updated the latest, newly added files on the main branch to also ship SPDX headers

[dartcafe]

Before we rebase frequently and in preparations for the upcomming changes, I vote for merging this.

[AndyScherzinger]

Before we rebase frequently and in preparations for the upcomming changes, I vote for merging this.

Fine by me of course. The reason I rebased were conflicts with the main branch and newly added files on master that didn't have SPDX headers. So while the PR is CI-green, after merging it to the main branch, any other newly created PR would be red given the REUSE Github action that would than fail.

[AndyScherzinger]

I would also say "can be merged", worst case we revert things or create follow-up PRs

[dartcafe]

Currently there are no relevant PRs targeting master. That's because "now" is a good time.

[AndyScherzinger]

Yes, again, fine to be merged from my pov - of course 👍

[dartcafe]

🤣 I assumed the author merges, not the reviewer.

[AndyScherzinger]

Ah, alright. I thought you would decide to merge at some point if @v1r0x wouldn't reply 😅

[AndyScherzinger]

In any way, very happy to have it in 🎉