Detect slipping on the PulseIndexZeroingEstimator

This only works after zeroing, not during, but it's a great start.

Change-Id: Ib3c9797a456b4181b82b47263020ba2120faf3d5
diff --git a/frc971/zeroing/zeroing.h b/frc971/zeroing/zeroing.h
index 91d5b8c..9d7cea1 100644
--- a/frc971/zeroing/zeroing.h
+++ b/frc971/zeroing/zeroing.h
@@ -276,8 +276,7 @@
   using ZeroingConstants = constants::EncoderPlusIndexZeroingConstants;
   using State = IndexEstimatorState;
 
-  PulseIndexZeroingEstimator(
-      const constants::EncoderPlusIndexZeroingConstants &constants)
+  PulseIndexZeroingEstimator(const ZeroingConstants &constants)
       : constants_(constants) {
     Reset();
   }
@@ -313,7 +312,7 @@
   int IndexPulseCount() const;
 
   // Contains the physical constants describing the system.
-  const constants::EncoderPlusIndexZeroingConstants constants_;
+  const ZeroingConstants constants_;
 
   // The smallest position of all the index pulses.
   double min_index_position_;