Rename PotAndAbsEncoder to be more consistent

$ git sed 's/AbsoluteEstimatorState/PotAndAbsoluteEncoderEstimatorState/'
$ git sed 's/PotAndAbsEncoderZeroingEstimator/PotAndAbsoluteEncoderZeroingEstimator/'

It's a bit all over the place in terms of naming and doesn't leave much
space to name something which is just an absolute encoder.

Change-Id: Iecbee91191bd9cc16eb08fd24b91335ef772beec
diff --git a/frc971/control_loops/control_loops.q b/frc971/control_loops/control_loops.q
index 03e93fd..bebecd0 100644
--- a/frc971/control_loops/control_loops.q
+++ b/frc971/control_loops/control_loops.q
@@ -65,7 +65,7 @@
 };
 
 // The internal state of a zeroing estimator.
-struct AbsoluteEstimatorState {
+struct PotAndAbsoluteEncoderEstimatorState {
   // If true, there has been a fatal error for the estimator.
   bool error;
   // If the joint has seen an index pulse and is zeroed.