msg: add filter internal fault message

msg/estimator_status.msg

@@ -32,3 +32,19 @@ uint16 control_mode_flags	# Bitmask to indicate EKF logic state
 # 11 - true when baro height is being fused as a primary height reference
 # 12 - true when range finder height is being fused as a primary height reference
 # 15 - true when range finder height is being fused as a primary height reference
+uint16 filter_fault_flags	# Bitmask to indicate EKF internal faults
+# 0 - true if the fusion of the magnetometer X-axis has encountered a numerical error
+# 1 - true if the fusion of the magnetometer Y-axis has encountered a numerical error
+# 2 - true if the fusion of the magnetometer Z-axis has encountered a numerical error
+# 3 - true if the fusion of the magnetic heading has encountered a numerical error
+# 4 - true if the fusion of the magnetic declination has encountered a numerical error
+# 5 - true if fusion of the airspeed has encountered a numerical error
+# 6 - true if fusion of the synthetic sideslip constraint has encountered a numerical error
+# 7 - true if fusion of the optical flow X axis has encountered a numerical error
+# 8 - true if fusion of the optical flow Y axis has encountered a numerical error
+# 9 - true if fusion of the North velocity has encountered a numerical error
+# 10 - true if fusion of the East velocity has encountered a numerical error
+# 11 - true if fusion of the Down velocity has encountered a numerical error
+# 12 - true if fusion of the North position has encountered a numerical error
+# 13 - true if fusion of the East position has encountered a numerical error
+# 14 - true if fusion of the Down position has encountered a numerical error