Relicensing Basalt.

Basalt is moving off MIT.

I do this project for fun, and I never minded people forking it or copying from it. What I do want is for changes to the app to come back, or at least stay in the open. MIT does not ask for that, so it was time for a change.

The app and the libraries now get different treatment.

basalt-tui, the application, is now GPL-3.0-or-later. It is copyleft, which means if you distribute a modified version it has to stay open under the same terms. That is the whole point.

basalt-core and basalt-widgets, the libraries, are now Apache-2.0. These are meant to be reused, so they stay permissive. Yes, that means someone can still take them closed. That is a deliberate trade I am happy to make for the libraries.

I also added a small Contributor License Agreement. You keep your copyright and agree to it by opening a pull request. It keeps things flexible if the licensing needs to change again later.

Nothing changes for versions already out there. If you have an MIT build, it stays MIT. The new terms apply from the next release onward.

Cheers!

— Erik