Export and import of control on-screen button settings.

[docent27]

I would like to be able to export and import on-screen button settings. Unfortunately, after reinstalling the APK, the settings are reset to default. I think the settings are stored in protected memory, which cannot be accessed without root rights. But it would be convenient if the on-screen button settings are stored in the same directory as other files, such as settings.cfg and openmw.cfg.