SDL_bgi 3.0.0

SDL_bgi is a graphics library (`GRAPHICS.H`) for C, C++, WebAssembly, and Python. SDL_bgi is fully compatible with BGI, the Borland Graphics Interface that was the de-facto standard in PC graphics back in DOS days. It's very easy to use, pretty fast, and it also provides extensions for ARGB colours, mouse support, vector fonts, and turtle graphics. It should run on any platform supported by SDL2.