Heading Geometry Update

Updated math to correctly constrain angle of heading in radians to be from -pi to pi.

Author: Grahldg

examples/LSM9DS1_Basic_SPI/LSM9DS1_Basic_SPI.ino

@@ -234,7 +234,6 @@ void printAttitude(float ax, float ay, float az, float mx, float my, float mz)
 
   if (heading > PI) heading -= (2 * PI);
   else if (heading < -PI) heading += (2 * PI);
-  else if (heading < 0) heading += 2 * PI;
 
   // Convert everything from radians to degrees:
   heading *= 180.0 / PI;