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/src/DigitalInput.cpp

@@ -0,0 +1,54 @@
+/*----------------------------------------------------------------------------*/
+/* 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.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "DigitalInput.h"
+#include "WPIErrors.h"
+
+/**
+ * Create an instance of a Digital Input class.
+ * Creates a digital input given a channel and uses the default module.
+ *
+ * @param channel The digital channel (1..14).
+ */
+DigitalInput::DigitalInput(uint32_t channel) {
+  char buf[64];
+  m_channel = channel;
+  int n = sprintf(buf, "dio/%d", channel);
+  m_impl = new SimDigitalInput(buf);
+}
+
+/**
+ * Get the value from a digital input channel.
+ * Retrieve the value of a single digital input channel from the FPGA.
+ */
+uint32_t DigitalInput::Get() const { return m_impl->Get(); }
+
+/**
+ * @return The GPIO channel number that this object represents.
+ */
+uint32_t DigitalInput::GetChannel() const { return m_channel; }
+
+void DigitalInput::UpdateTable() {
+  if (m_table != nullptr) {
+    m_table->PutBoolean("Value", Get());
+  }
+}
+
+void DigitalInput::StartLiveWindowMode() {}
+
+void DigitalInput::StopLiveWindowMode() {}
+
+std::string DigitalInput::GetSmartDashboardType() const {
+  return "DigitalInput";
+}
+
+void DigitalInput::InitTable(std::shared_ptr<ITable> subTable) {
+  m_table = subTable;
+  UpdateTable();
+}
+
+std::shared_ptr<ITable> DigitalInput::GetTable() const { return m_table; }