proposal: REUSE compliance

[wtraylor]

Currently, Popper’s Git repository is under the MIT license, which resides in the LICENSE file. That is common practice for open-source projects, but it has several drawbacks:

1. The software license (MIT) doesn’t work well for media and text, which are also in the Popper repo. Creative Commons are specifically designed for media and text.
2. A single file copied from the repository loses its licensing information because it’s not in the file itself.
3. The copyright holders are not obvious. One would have to go through the Git log in order to find who contributed substantially (more than just removing a blank line for instance).
4. Even insignificant content requires attribution (under the MIT license) where it would make more sense to place them in the public domain, e.g. .gitignore.

For these reasons (in particular the first one!) I suggest to make the Popper repository REUSE-compliant. REUSE is a standard from the Free Software Foundation Europe (FSFE). The website offers various resources, a tutorial, and tools.

I think it is crucial to do this now because it requires consent by the contributors to change a license, and the older a project gets the more difficult that becomes. For text and media files (images and Markdown texts) I suggest to move from MIT to CC-BY.

[ivotron]

thanks @wtraylor ! this is a great suggestion and I think we should do it!