Test & Evaluate Joystick Sensitivity

Before release 2.1, we need to test and evaluate the joystick sensitivity setting in the menus.  This verifies the SFML port behaves correctly for this.  The baseline for correct behavior is generally what it did in release 2.0 when it used SDL.  Some code comparison may be required, comparing the SDL code versus the SFML code, as part of the evaluation, as well as referencing API documentation.