Bugfix: Make SF work with older Android versions
Manual freeze: Tell the user to press "Force stop", "OK" and "Back", fix #14
Add screenshots
Do not auto freeze SuperFreezZ itself
Only regard an app as 'used' if it was used at least 2s
Repair determination whether an app was "used recently"
Do not show AutoFreeze/Freeze-when-inactive - button (I should really decide for ONE name btw) when usagestats permission is not granted
Improve accessibility service chooser fragment
