Major plugin refactor and cleanup.

Switched to POCO library for unified platform/library interface.
Deprecated the external module API. It was creating more problems than solving.
Removed most built-in libraries in favor of system libraries for easier maintenance.
Cleaned and secured code with help from static analyzers.

vendor/POCO/Foundation/include/Poco/TaskManager.h

@@ -0,0 +1,137 @@
+//
+// TaskManager.h
+//
+// Library: Foundation
+// Package: Tasks
+// Module:  Tasks
+//
+// Definition of the TaskManager class.
+//
+// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
+// and Contributors.
+//
+// SPDX-License-Identifier:	BSL-1.0
+//
+
+
+#ifndef Foundation_TaskManager_INCLUDED
+#define Foundation_TaskManager_INCLUDED
+
+
+#include "Poco/Foundation.h"
+#include "Poco/Mutex.h"
+#include "Poco/Task.h"
+#include "Poco/AutoPtr.h"
+#include "Poco/NotificationCenter.h"
+#include "Poco/Timestamp.h"
+#include <list>
+
+
+namespace Poco {
+
+
+class Notification;
+class ThreadPool;
+class Exception;
+
+
+class Foundation_API TaskManager
+	/// The TaskManager manages a collection of tasks
+	/// and monitors their lifetime.
+	///
+	/// A TaskManager has a built-in NotificationCenter that
+	/// is used to send out notifications on task progress
+	/// and task states. See the TaskNotification class and its
+	/// subclasses for the various events that result in a notification.
+	/// To keep the number of notifications small, a TaskProgressNotification
+	/// will only be sent out once in 100 milliseconds.
+{
+public:
+	using TaskPtr = AutoPtr<Task>;
+	using TaskList = std::list<TaskPtr>;
+
+	TaskManager();
+		/// Creates the TaskManager, using the
+		/// default ThreadPool.
+
+	TaskManager(ThreadPool& pool);
+		/// Creates the TaskManager, using the
+		/// given ThreadPool.
+
+	~TaskManager();
+		/// Destroys the TaskManager.
+
+	void start(Task* pTask);
+		/// Starts the given task in a thread obtained
+		/// from the thread pool.
+		///
+		/// The TaskManager takes ownership of the Task object
+		/// and deletes it when it it finished.
+
+	void cancelAll();
+		/// Requests cancellation of all tasks.
+		
+	void joinAll();
+		/// Waits for the completion of all the threads
+		/// in the TaskManager's thread pool.
+		///
+		/// Note: joinAll() will wait for ALL tasks in the
+		/// TaskManager's ThreadPool to complete. If the
+		/// ThreadPool has threads created by other
+		/// facilities, these threads must also complete
+		/// before joinAll() can return.
+
+	TaskList taskList() const;
+		/// Returns a copy of the internal task list.
+
+	int count() const;
+		/// Returns the number of tasks in the internal task list.
+
+	void addObserver(const AbstractObserver& observer);
+		/// Registers an observer with the NotificationCenter.
+		/// Usage:
+		///     Observer<MyClass, MyNotification> obs(*this, &MyClass::handleNotification);
+		///     notificationCenter.addObserver(obs);
+
+	void removeObserver(const AbstractObserver& observer);
+		/// Unregisters an observer with the NotificationCenter.
+
+	static const int MIN_PROGRESS_NOTIFICATION_INTERVAL;
+
+protected:
+	void postNotification(const Notification::Ptr& pNf);
+		/// Posts a notification to the task manager's 
+		/// notification center.
+
+	void taskStarted(Task* pTask);
+	void taskProgress(Task* pTask, float progress);
+	void taskCancelled(Task* pTask);
+	void taskFinished(Task* pTask);
+	void taskFailed(Task* pTask, const Exception& exc);
+
+private:
+	ThreadPool&        _threadPool;
+	TaskList           _taskList;
+	Timestamp          _lastProgressNotification;
+	NotificationCenter _nc;
+	mutable FastMutex  _mutex;
+
+	friend class Task;
+};
+
+
+//
+// inlines
+//
+inline int TaskManager::count() const
+{
+	FastMutex::ScopedLock lock(_mutex);
+
+	return (int) _taskList.size();
+}
+
+
+} // namespace Poco
+
+
+#endif // Foundation_TaskManager_INCLUDED