Fixed bug where kalman filter was being coppied rather than passed by pointer.

Change-Id: Ib2d0fa0ec2e5a0b19592ca419fec339252a3f698
diff --git a/frc971/control_loops/drivetrain/drivetrain.q b/frc971/control_loops/drivetrain/drivetrain.q
index 7fa91b9..24b1d38 100644
--- a/frc971/control_loops/drivetrain/drivetrain.q
+++ b/frc971/control_loops/drivetrain/drivetrain.q
@@ -112,6 +112,10 @@
     double uncapped_left_voltage;
     double uncapped_right_voltage;
 
+    // The goal velocities for the polydrive controller.
+    double left_velocity_goal;
+    double right_velocity_goal;
+
     // True if the output voltage was capped last cycle.
     bool output_was_capped;
   };