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/Poco.h

@@ -0,0 +1,24 @@
+//
+// Poco.h
+//
+// Library: Foundation
+// Package: Core
+// Module:  Foundation
+//
+// Basic definitions for the POCO libraries.
+//
+// Copyright (c) 2006, Applied Informatics Software Engineering GmbH.
+// and Contributors.
+//
+// SPDX-License-Identifier:	BSL-1.0
+//
+
+
+#ifndef Foundation_Poco_INCLUDED
+#define Foundation_Poco_INCLUDED
+
+
+#include "Poco/Foundation.h"
+
+
+#endif // Foundation_Poco_INCLUDED