Add new C++ Command framework (#1785)

This is the C++ version of #1682.

The old command framework is still available, but will be deprecated.

Due to name conflicts, the new framework is in the frc2 namespace.
Eventually (after the old command framework is removed in a future year)
it will be moved into the main frc namespace.

wpilibcExamples/src/main/cpp/examples/GearsBotNew/include/subsystems/Wrist.h

@@ -0,0 +1,62 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2017-2019 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#pragma once
+
+#include <frc2/command/PIDSubsystem.h>
+
+#include <frc/AnalogPotentiometer.h>
+#include <frc/PWMVictorSPX.h>
+
+/**
+ * The wrist subsystem is like the elevator, but with a rotational joint instead
+ * of a linear joint.
+ */
+class Wrist : public frc2::PIDSubsystem {
+ public:
+  Wrist();
+
+  /**
+   * The log method puts interesting information to the SmartDashboard.
+   */
+  void Log();
+
+  /**
+   * Use the potentiometer as the PID sensor. This method is automatically
+   * called by the subsystem.
+   */
+  double GetMeasurement() override;
+
+  /**
+   * Use the motor as the PID output. This method is automatically called
+   * by
+   * the subsystem.
+   */
+  void UseOutput(double d) override;
+
+  double GetSetpoint() override;
+
+  /**
+   * Sets the setpoint for the subsystem.
+   */
+  void SetSetpoint(double setpoint);
+
+ private:
+  frc::PWMVictorSPX m_motor{6};
+  double m_setpoint = 0;
+
+// Conversion value of potentiometer varies between the real world and
+// simulation
+#ifndef SIMULATION
+  frc::AnalogPotentiometer m_pot{3, -270.0 / 5};
+#else
+  frc::AnalogPotentiometer m_pot{3};  // Defaults to degrees
+#endif
+
+  static constexpr double kP_real = 1;
+  static constexpr double kP_simulation = 0.05;
+};