Renamed folders for consistency, using sim/athena/shared schema (#27)

Rename the following folders:
hal/lib/Athena -> hal/lib/athena
hal/lib/Desktop -> hal/lib/sim
hal/lib/Shared -> hal/lib/shared
wpilibc/Athena -> wpilibc/athena
wpilibc/simulation -> wpilibc/sim

Windows users may need to run gradlew clean after updating.

wpilibc/sim/include/SpeedController.h

@@ -0,0 +1,36 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) FIRST 2008-2016. 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 "PIDOutput.h"
+
+/**
+ * Interface for speed controlling devices.
+ */
+class SpeedController : public PIDOutput {
+ public:
+  virtual ~SpeedController() = default;
+  /**
+   * Common interface for setting the speed of a speed controller.
+   *
+   * @param speed     The speed to set.  Value should be between -1.0 and 1.0.
+   * @param syncGroup The update group to add this Set() to, pending
+   *                  UpdateSyncGroup().  If 0, update immediately.
+   */
+  virtual void Set(float speed, uint8_t syncGroup = 0) = 0;
+  /**
+   * Common interface for getting the current set speed of a speed controller.
+   *
+   * @return The current set speed.  Value is between -1.0 and 1.0.
+   */
+  virtual float Get() const = 0;
+  /**
+   * Common interface for disabling a motor.
+   */
+  virtual void Disable() = 0;
+};