Added filtered absolute encoder.

Change-Id: I2b22f251b4585e3cc93d0ad10a1cf7e80dc6731b
diff --git a/frc971/control_loops/control_loops.q b/frc971/control_loops/control_loops.q
index cb95df8..4d87587 100644
--- a/frc971/control_loops/control_loops.q
+++ b/frc971/control_loops/control_loops.q
@@ -75,6 +75,10 @@
 
   // The estimated position not using the index pulse.
   double pot_position;
+
+  // The estimated absolute position of the encoder.  This is filtered, so it
+  // can be easily used when zeroing.
+  double absolute_position;
 };
 
 // The internal state of a zeroing estimator.