Usage of Instances and IDs dealing with joysticks and controllers

[alexispaez]

SDL.Inputs.Joysticks.Instance returns a type Instances. The Instances type is mapped to SDL2's SDL_JoystickID and defined in SDL.Inputs.Joysticks as

   type Instances is range 0 .. 2 ** 31 - 1 with
     Convention => C,
     Size       => 32;

On the other hand, the events for Axis, Button and Device all have the "which" member defined as an IDs, which is as defined in SDL.Events.Joysticks as:

   type IDs is range -2 ** 31 .. 2 ** 31 - 1 with
     Convention => C,
     Size       => 32;

This forces a cast when checking the joystick events, I think that both could be made the same. There doesn't seem to be any other uses for SDL.Events.Joysticks.IDs anywhere else in the current sdlada codebase.