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/samples/Activity/src/Activity.cpp

@@ -0,0 +1,68 @@
+//
+// Activity.cpp
+//
+// This sample demonstrates the Activity class.
+//
+// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
+// and Contributors.
+//
+// SPDX-License-Identifier:	BSL-1.0
+//
+
+
+#include "Poco/Activity.h"
+#include "Poco/Thread.h"
+#include <iostream>
+
+
+using Poco::Activity;
+using Poco::Thread;
+
+
+class ActivityExample
+{
+public:
+	ActivityExample():
+		_activity(this, &ActivityExample::runActivity)
+	{
+	}
+	
+	void start()
+	{
+		_activity.start();
+	}
+	
+	void stop()
+	{
+		_activity.stop();
+		_activity.wait();
+	}
+
+protected:
+	void runActivity()
+	{
+		while (!_activity.isStopped())
+		{
+			std::cout << "Activity running." << std::endl;
+			Thread::sleep(250);
+		}
+		std::cout << "Activity stopped." << std::endl;
+	}
+	
+private:
+	Activity<ActivityExample> _activity;
+};
+
+
+int main(int argc, char** argv)
+{
+	ActivityExample example;
+	example.start();
+	Thread::sleep(2000);
+	example.stop();
+
+	example.start();
+	example.stop();
+
+	return 0;
+}