delete SYS_MC_EST_GROUP

- introduce per module parameters (EKF2_EN, LPE_EN, ATT_EN)
 - add basic checks to prevent EKF2 + LPE running simultaneously

src/modules/attitude_estimator_q/attitude_estimator_q_main.cpp

@@ -180,6 +180,14 @@ AttitudeEstimatorQ::AttitudeEstimatorQ() :
 
 bool AttitudeEstimatorQ::init()
 {
+	uORB::SubscriptionData<vehicle_attitude_s> vehicle_attitude_sub{ORB_ID(vehicle_attitude)};
+	vehicle_attitude_sub.update();
+
+	if (vehicle_attitude_sub.advertised() && (hrt_elapsed_time(&vehicle_attitude_sub.get().timestamp) < 1_s)) {
+		PX4_ERR("init failed, vehicle_attitude already advertised");
+		return false;
+	}
+
 	if (!_sensors_sub.registerCallback()) {
 		PX4_ERR("callback registration failed");
 		return false;

src/modules/attitude_estimator_q/attitude_estimator_q_params.c

@@ -39,6 +39,16 @@
  * @author Anton Babushkin <anton.babushkin@me.com>
  */
 
+/**
+ * standalone attitude estimator enable (unsupported)
+ *
+ * Enable standalone quaternion based attitude estimator.
+ *
+ * @group Attitude Q estimator
+ * @boolean
+ */
+PARAM_DEFINE_INT32(ATT_EN, 0);
+
 /**
  * Complimentary filter accelerometer weight
  *