Split the two command implementations into separate libraries (#2012)

This will allow us at the user code side to determine to include old commands, new commands or both.

wpilibNewCommands/src/main/native/include/frc2/command/FunctionalCommand.h

@@ -0,0 +1,56 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 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 "CommandBase.h"
+#include "CommandHelper.h"
+
+namespace frc2 {
+/**
+ * A command that allows the user to pass in functions for each of the basic
+ * command methods through the constructor.  Useful for inline definitions of
+ * complex commands - note, however, that if a command is beyond a certain
+ * complexity it is usually better practice to write a proper class for it than
+ * to inline it.
+ */
+class FunctionalCommand : public CommandHelper<CommandBase, FunctionalCommand> {
+ public:
+  /**
+   * Creates a new FunctionalCommand.
+   *
+   * @param onInit       the function to run on command initialization
+   * @param onExecute    the function to run on command execution
+   * @param onEnd        the function to run on command end
+   * @param isFinished   the function that determines whether the command has
+   * finished
+   * @param requirements the subsystems required by this command
+   */
+  FunctionalCommand(std::function<void()> onInit,
+                    std::function<void()> onExecute,
+                    std::function<void(bool)> onEnd,
+                    std::function<bool()> isFinished);
+
+  FunctionalCommand(FunctionalCommand&& other) = default;
+
+  FunctionalCommand(const FunctionalCommand& other) = default;
+
+  void Initialize() override;
+
+  void Execute() override;
+
+  void End(bool interrupted) override;
+
+  bool IsFinished() override;
+
+ private:
+  std::function<void()> m_onInit;
+  std::function<void()> m_onExecute;
+  std::function<void(bool)> m_onEnd;
+  std::function<bool()> m_isFinished;
+};
+}  // namespace frc2