Use explicit flatbuffer IDs in y2017 and newer.

Non-explicit ids are risky.  We've seen backwards incompatible
changes...

Change-Id: Id6ceebe031ac80430191f367635d0e951c3d2cbc
diff --git a/y2019/control_loops/superstructure/superstructure_status.fbs b/y2019/control_loops/superstructure/superstructure_status.fbs
index 9d3f44e..98fe483 100644
--- a/y2019/control_loops/superstructure/superstructure_status.fbs
+++ b/y2019/control_loops/superstructure/superstructure_status.fbs
@@ -5,19 +5,19 @@
 
 table Status {
   // All subsystems know their location.
-  zeroed:bool;
+  zeroed:bool (id: 0);
 
   // If true, we have aborted. This is the or of all subsystem estops.
-  estopped:bool;
+  estopped:bool (id: 1);
 
   // Whether suction_pressure indicates cargo is held
-  has_piece:bool;
+  has_piece:bool (id: 2);
 
   // Status of each subsystem.
-  elevator:frc971.control_loops.PotAndAbsoluteEncoderProfiledJointStatus;
-  wrist:frc971.control_loops.PotAndAbsoluteEncoderProfiledJointStatus;
-  intake:frc971.control_loops.AbsoluteEncoderProfiledJointStatus;
-  stilts:frc971.control_loops.PotAndAbsoluteEncoderProfiledJointStatus;
+  elevator:frc971.control_loops.PotAndAbsoluteEncoderProfiledJointStatus (id: 3);
+  wrist:frc971.control_loops.PotAndAbsoluteEncoderProfiledJointStatus (id: 4);
+  intake:frc971.control_loops.AbsoluteEncoderProfiledJointStatus (id: 5);
+  stilts:frc971.control_loops.PotAndAbsoluteEncoderProfiledJointStatus (id: 6);
 }
 
 root_type Status;