add phone tilt support for scrolling

[Atreyagaurav]

I've wanted to make this simple app for s long time but I can't do android development well. But this is a feature I think would be very useful. Make it take the phone tilt information and continuously send scross event based on that. The configuration settings can have sensitivity and interval between scroll events. But I think that'd give an easy way to have auto scroll while also being able to control the speed. Horizontal scroll can be added later when you add it for other one.

I don't have android development kits, or experience otherwise I'd have liked to contribute.