Add zeroing state to claw status messages.

Change-Id: I0144cb1455a3de5abca45e071c22f59cd4631e3f
diff --git a/frc971/control_loops/control_loops.q b/frc971/control_loops/control_loops.q
index 03929a2..bf2b27a 100644
--- a/frc971/control_loops/control_loops.q
+++ b/frc971/control_loops/control_loops.q
@@ -21,6 +21,16 @@
   uint32_t index_pulses;
 };
 
+// The internal state of a zeroing estimator.
+struct EstimatorState {
+  // If true, there has been a fatal error for the estimator.
+  bool error;
+  // If the joint has seen an index pulse and is zeroed.
+  bool zeroed;
+  // The estimated position of the joint.
+  double position;
+};
+
 // A left/right pair of PotAndIndexPositions.
 struct PotAndIndexPair {
   PotAndIndexPosition left;