horny desktop pet thing.

you need sdl3 to build it.
i have not tried cross-compiling to windows yet.

i think it's probably best to use some sort of extension language.
i want people to be able to create their own pets without having to
figure out how to recompile.

run it with `SDL_LOGGING=app=debug ./slutpet` for verbose logging

file layout:

dat.h - data structure header
fns.h - functions and macros header

slutpet.c - sdl init and close
img.c - loading images
samply.c - pet Samply