Filtering compass changes in Android

[erf]

I've added a low pass filter for averaging compass directional changes, i also use time and angle to limit these updates. Used in the MapboxGLAndroidSDKTestApp.

Improvement for issue #1676

[ljbade]

Tried testing it on my Sony Z3 but unfortunately today the compass sensor does not want to co-operate - was point in every direction but the right one (was doing the same thing in Google Maps)

Looking at the code, can you make a few tweaks:

• use camelCase for the variable names
• remove the commented out lines

[erf]

I also had compass problems on S3, but it's much better on nexus 7. Maybe the algorithm can be improved upon.

[bleege]

Thanks @erf! Moving to 0.2.0 for now though.

[tobrun]

@erf
I wanted to thank you for this contribution, I have been playing around with your suggestion. Your code has helped me a lot on setting this up but I must mention I have removed it again. Instead I'm rate limiting the sensor input and I'm seeing great improvements on lowering memory churn.

[erf]

@tobrun No worries! I'm glad you are doing progress.