SPDX standardizes how source code conveys its copyright and licensing
information. See https://spdx.github.io/spdx-spec/1-rationale/ . SPDX
tags are adopted in many large projects, including things like the Linux
kernel.
The SDL backend crashes when you close a joystick after SDL_Quit has
been called. Some backends don't need to be shutdown and
re-initialized everytime, we can just ask to enumerate devices again.
