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/CounterBase.h

@@ -0,0 +1,30 @@
+/*----------------------------------------------------------------------------*/
+/* 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
+
+/**
+ * Interface for counting the number of ticks on a digital input channel.
+ *
+ * Encoders, Gear tooth sensors, and counters should all subclass this so it can
+ * be used to build more advanced classes for control and driving.
+ *
+ * All counters will immediately start counting - Reset() them if you need them
+ * to be zeroed before use.
+ */
+class CounterBase {
+ public:
+  enum EncodingType { k1X, k2X, k4X };
+
+  virtual ~CounterBase() = default;
+  virtual int32_t Get() const = 0;
+  virtual void Reset() = 0;
+  virtual double GetPeriod() const = 0;
+  virtual void SetMaxPeriod(double maxPeriod) = 0;
+  virtual bool GetStopped() const = 0;
+  virtual bool GetDirection() const = 0;
+};