[wpilib] Move motor controllers to motorcontrol package (#3302)

Also deprecate SpeedController in favor of motorcontrol.MotorController and
SpeedControllerGroup in favor of motorcontrol.MotorControllerGroup.

The MotorController interface is derived from the SpeedController interface
so that code such as SpeedController x = new VictorSP(1) continues to
compile (just with a warning).

SpeedControllerGroup and MotorControllerGroup are independent classes;
both implement the MotorController interface.

wpilibc/src/main/native/include/frc/motorcontrol/Spark.h

@@ -0,0 +1,41 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+#pragma once
+
+#include "frc/motorcontrol/PWMMotorController.h"
+
+namespace frc {
+
+/**
+ * REV Robotics SPARK Motor Controller.
+ *
+ * Note that the SPARK uses the following bounds for PWM values. These values
+ * should work reasonably well for most controllers, but if users experience
+ * issues such as asymmetric behavior around the deadband or inability to
+ * saturate the controller in either direction, calibration is recommended.
+ * The calibration procedure can be found in the SPARK User Manual available
+ * from REV Robotics.
+ *
+ * \li 2.003ms = full "forward"
+ * \li 1.550ms = the "high end" of the deadband range
+ * \li 1.500ms = center of the deadband range (off)
+ * \li 1.460ms = the "low end" of the deadband range
+ * \li 0.999ms = full "reverse"
+ */
+class Spark : public PWMMotorController {
+ public:
+  /**
+   * Constructor for a SPARK.
+   *
+   * @param channel The PWM channel that the SPARK is attached to. 0-9 are
+   *                on-board, 10-19 are on the MXP port
+   */
+  explicit Spark(int channel);
+
+  Spark(Spark&&) = default;
+  Spark& operator=(Spark&&) = default;
+};
+
+}  // namespace frc