added ground_course in proper 0-360 degrees * 100 for Ardupilot

git-svn-id: https://arducopter.googlecode.com/svn/trunk@348 f9c3cf11-9bcb-44bc-f272-b75c42450872

libraries/AP_Compass/AP_Compass.cpp

@@ -107,6 +107,7 @@ AP_Compass::calculate(float roll, float pitch)
 	
 	// Magnetic heading
 	heading = atan2(-head_Y, head_X);
+	ground_course = degrees(heading) + 180;
 	
 	// Optimization for external DCM use. calculate normalized components
 	heading_X = cos(heading);

libraries/AP_Compass/Compass.h

@@ -13,6 +13,7 @@ class Compass
 	int16_t mag_X;
 	int16_t mag_Y;
 	int16_t mag_Z;
+	int32_t ground_course;
 	float heading;
 	float heading_X;
 	float heading_Y;