Gamma ramp
The ability to manage display gamma ramps should be added.
Consider converting to/from u16vector, or adding a sdl-gamma-ramp type that wraps the pointer, so that the user does not need to handle raw pointers to C arrays.
Note that SDL_GetWindowBrightness and SDL_SetWindowBrightness (aka sdl-window-brightness
and sdl-window-brightness-set!
) provide a simpler (but less flexible) interface for getting and setting the display gamma.