title: Using orientation sensor to point towards a specific location
body: <p>I'm trying to implement an arrow that uses the orientation sensor in order to point towards a specific location. Google Places implements this arrow in a ListView for each place it finds.</p>
  
  <p>I've managed to get the azimuth, but given a location, I don't know how to proceed to calculate the angle I need. Moreover, I need to make the conversions from real north and magnetic north. Does anybody have an example of such implementation?</p>
  
  <p>Thanks in advance.</p>