Made Yaw Hold universal for Acro

ArduCopter/system.pde

@@ -206,7 +206,7 @@ static void init_ardupilot()
     // identify ourselves correctly with the ground station
 	mavlink_system.sysid = g.sysid_this_mav;
     mavlink_system.type = 2; //MAV_QUADROTOR;
-        
+
 #if LOGGING_ENABLED == ENABLED
     DataFlash.Init();
     if (!DataFlash.CardInserted()) {
@@ -448,7 +448,7 @@ static void set_mode(byte mode)
 	switch(control_mode)
 	{
 		case ACRO:
-			yaw_mode 		= YAW_ACRO;
+			yaw_mode 		= YAW_HOLD;
 			roll_pitch_mode = ROLL_PITCH_ACRO;
 			throttle_mode 	= THROTTLE_MANUAL;
 			break;