Airspy controller - changes method for adjusting center tuned frequency

when tuner channels are allocated by the airspy.  New method determines
the min/max requested frequency range and sets tuner center to the
center of that range, while limiting the total usable bandwidth to 90%
of the bandwidth, to account for rolloff of 5% at the upper/lower edges.

When a new channel is requested, if the channel fits within the current
center frequency and usable bandwidth, the center tune frequency is not
adjusted, to minimize the number of retunes on a busy system.

src/source/tuner/TunerController.java

@@ -114,7 +114,7 @@ public abstract class TunerController implements Tunable
 	
 	public long getMinTunedFrequency()
 	{
-		return mFrequencyController.getFrequency() - 
+		return mFrequencyController.getFrequency() -
 			   ( mFrequencyController.getBandwidth() / 2 );
 	}