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/src/BuiltInAccelerometer.cpp

@@ -0,0 +1,71 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) FIRST 2014-2016. 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.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "BuiltInAccelerometer.h"
+#include "HAL/HAL.hpp"
+#include "LiveWindow/LiveWindow.h"
+#include "WPIErrors.h"
+
+/**
+ * Constructor.
+ *
+ * @param range The range the accelerometer will measure
+ */
+BuiltInAccelerometer::BuiltInAccelerometer(Range range) {
+  SetRange(range);
+
+  HALReport(HALUsageReporting::kResourceType_Accelerometer, 0, 0,
+            "Built-in accelerometer");
+  LiveWindow::GetInstance()->AddSensor((std::string) "BuiltInAccel", 0, this);
+}
+
+void BuiltInAccelerometer::SetRange(Range range) {
+  if (range == kRange_16G) {
+    wpi_setWPIErrorWithContext(
+        ParameterOutOfRange, "16G range not supported (use k2G, k4G, or k8G)");
+  }
+
+  setAccelerometerActive(false);
+  setAccelerometerRange((AccelerometerRange)range);
+  setAccelerometerActive(true);
+}
+
+/**
+ * @return The acceleration of the RoboRIO along the X axis in g-forces
+ */
+double BuiltInAccelerometer::GetX() { return getAccelerometerX(); }
+
+/**
+ * @return The acceleration of the RoboRIO along the Y axis in g-forces
+ */
+double BuiltInAccelerometer::GetY() { return getAccelerometerY(); }
+
+/**
+ * @return The acceleration of the RoboRIO along the Z axis in g-forces
+ */
+double BuiltInAccelerometer::GetZ() { return getAccelerometerZ(); }
+
+std::string BuiltInAccelerometer::GetSmartDashboardType() const {
+  return "3AxisAccelerometer";
+}
+
+void BuiltInAccelerometer::InitTable(std::shared_ptr<ITable> subtable) {
+  m_table = subtable;
+  UpdateTable();
+}
+
+void BuiltInAccelerometer::UpdateTable() {
+  if (m_table != nullptr) {
+    m_table->PutNumber("X", GetX());
+    m_table->PutNumber("Y", GetY());
+    m_table->PutNumber("Z", GetZ());
+  }
+}
+
+std::shared_ptr<ITable> BuiltInAccelerometer::GetTable() const {
+  return m_table;
+}