Add software licence

[TerrorBite]

Code is currently unlicensed. In its current WIP state this is not an issue, but once it improves I probably want to apply the MIT License.

GitHub says:

You're under no obligation to choose a license. However, without a license, the default copyright laws apply, meaning that you retain all rights to your source code and no one may reproduce, distribute, or create derivative works from your work.