Add a License

[MassiminoilTrace]

Hello, first, thanks for your project

I'm using your library in a personal project, but I can't publish it, not even as open source, because it lacks a license.

I usually suggest using a GNU GPL3 license so your work can't be turned into a proprietary version by others, but this choice is entirely up to you as you are the author.

Let me know if i can help in some way for this issue