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.

hal/lib/athena/Semaphore.cpp

@@ -0,0 +1,55 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) FIRST 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 "HAL/Semaphore.hpp"
+
+#include "Log.hpp"
+
+// set the logging level
+TLogLevel semaphoreLogLevel = logDEBUG;
+
+#define SEMAPHORE_LOG(level)     \
+  if (level > semaphoreLogLevel) \
+    ;                            \
+  else                           \
+  Log().Get(level)
+
+extern "C" {
+
+MUTEX_ID initializeMutexNormal() { return new priority_mutex; }
+
+void deleteMutex(MUTEX_ID sem) { delete sem; }
+
+/**
+ * Lock the mutex, blocking until it's available.
+ */
+void takeMutex(MUTEX_ID mutex) { mutex->lock(); }
+
+/**
+ * Attempt to lock the mutex.
+ * @return true if succeeded in locking the mutex, false otherwise.
+ */
+bool tryTakeMutex(MUTEX_ID mutex) { return mutex->try_lock(); }
+
+/**
+ * Unlock the mutex.
+ * @return 0 for success, -1 for error. If -1, the error will be in errno.
+ */
+void giveMutex(MUTEX_ID mutex) { mutex->unlock(); }
+
+MULTIWAIT_ID initializeMultiWait() { return new priority_condition_variable; }
+
+void deleteMultiWait(MULTIWAIT_ID cond) { delete cond; }
+
+void takeMultiWait(MULTIWAIT_ID cond, MUTEX_ID m) {
+  std::unique_lock<priority_mutex> lock(*m);
+  cond->wait(lock);
+}
+
+void giveMultiWait(MULTIWAIT_ID cond) { cond->notify_all(); }
+
+}  // extern "C"