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/Runnable.h

@@ -0,0 +1,45 @@
+//
+// Runnable.h
+//
+// Library: Foundation
+// Package: Threading
+// Module:  Thread
+//
+// Definition of the Runnable class.
+//
+// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
+// and Contributors.
+//
+// SPDX-License-Identifier:	BSL-1.0
+//
+
+
+#ifndef Foundation_Runnable_INCLUDED
+#define Foundation_Runnable_INCLUDED
+
+
+#include "Poco/Foundation.h"
+
+
+namespace Poco {
+
+
+class Foundation_API Runnable
+	/// The Runnable interface with the run() method
+	/// must be implemented by classes that provide
+	/// an entry point for a thread.
+{
+public:	
+	Runnable();
+	virtual ~Runnable();
+	
+	virtual void run() = 0;
+		/// Do whatever the thread needs to do. Must
+		/// be overridden by subclasses.
+};
+
+
+} // namespace Poco
+
+
+#endif // Foundation_Runnable_INCLUDED