The render target usage in controllermap is required if you are forced to use
the app at a different resolution than the one the art has been made for, for
example on Android, where you don't control the resolution.
(The coordinates for each button are hardcoded to the art size, and appear out
of place otherwise)
SDL_GameControllerAddMappingsFromFile is now a convenience macro.
controllermap can now skip bindings by pressing space or clicking/touching the
screen.
