Created a spline drivetrain.

Change-Id: Icfbfcec930d17d1a2ca075fc2eb67594d35113df
diff --git a/frc971/control_loops/drivetrain/drivetrain.cc b/frc971/control_loops/drivetrain/drivetrain.cc
index a50b429..ec9faaa 100644
--- a/frc971/control_loops/drivetrain/drivetrain.cc
+++ b/frc971/control_loops/drivetrain/drivetrain.cc
@@ -38,6 +38,7 @@
       kf_(dt_config_.make_kf_drivetrain_loop()),
       dt_openloop_(dt_config_, &kf_),
       dt_closedloop_(dt_config_, &kf_, &integrated_kf_heading_),
+      dt_spline_(dt_config_),
       down_estimator_(MakeDownEstimatorLoop()),
       left_gear_(dt_config_.default_high_gear ? Gear::HIGH : Gear::LOW),
       right_gear_(dt_config_.default_high_gear ? Gear::HIGH : Gear::LOW),
@@ -329,6 +330,7 @@
 
     dt_closedloop_.SetGoal(*goal);
     dt_openloop_.SetGoal(*goal);
+    dt_spline_.SetGoal(*goal);
   }
 
   dt_openloop_.Update(robot_state().voltage_battery);
@@ -342,6 +344,9 @@
     case 1:
       dt_closedloop_.SetOutput(output);
       break;
+    case 2:
+      dt_spline_.SetOutput(output);
+      break;
   }
 
   // The output should now contain the shift request.