Safe experimental mode with auto revert

[klues]

For users who are depending on FABI/FLipMouse as primary input device there should be a safe experimental mode where they can adjust settings without the risk of lock themselves out. This is how it could work:

1. users can activate "safe mode" in general settings
2. if activated after each change of settings a timer starts counting down on the bottom edge, e.g. 2 minutes
3. if another setting is made, the timer restarts
4. if the timer reaches zero, the configuration is resetted to the initial config
5. if the config is fine, the user can stop the timer in order to keep the settings