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/athena/include/DigitalSource.h

@@ -0,0 +1,28 @@
+/*----------------------------------------------------------------------------*/
+/* 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 "InterruptableSensorBase.h"
+
+/**
+ * DigitalSource Interface.
+ * The DigitalSource represents all the possible inputs for a counter or a
+ * quadrature encoder. The source may be
+ * either a digital input or an analog input. If the caller just provides a
+ * channel, then a digital input will be
+ * constructed and freed when finished for the source. The source can either be
+ * a digital input or analog trigger
+ * but not both.
+ */
+class DigitalSource : public InterruptableSensorBase {
+ public:
+  virtual ~DigitalSource() = default;
+  virtual uint32_t GetChannelForRouting() const = 0;
+  virtual uint32_t GetModuleForRouting() const = 0;
+  virtual bool GetAnalogTriggerForRouting() const = 0;
+};