[AD] Android Gamepads

[Trent Gamblin <trent@xxxxxxxxxx>]

For some reason, I guess because gamepads weren't common on Android/iOS, 
those ports use the accelerometer for the joystick.

This is becoming a problem. On OUYA you can actually access the 
/dev/input device for the joystick, but on other devices you can't. What 
other devices? There's Fire TV, tablets with gamepads connected, SHIELD 
and any time now (I have this confirmed) a Google console. Plus on OUYA 
/dev/input isn't reliable because the "menu" button doesn't work.

So I'm proposing that we support real joysticks on Android instead of 
accelerometer. It's a standard interface on Android that works across 
all devices. However, it requires Android 3.1.

Accelerometer could be given its own event source if anyone can come up 
with an API.