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/XML/samples/PrettyPrint/src/PrettyPrint.cpp

@@ -0,0 +1,56 @@
+//
+// PrettyPrint.cpp
+//
+// This sample demonstrates the SAXParser, WhitespaceFilter,
+// InputSource and XMLWriter classes.
+//
+// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
+// and Contributors.
+//
+// SPDX-License-Identifier:	BSL-1.0
+//
+
+
+#include "Poco/SAX/SAXParser.h"
+#include "Poco/SAX/WhitespaceFilter.h"
+#include "Poco/SAX/InputSource.h"
+#include "Poco/XML/XMLWriter.h"
+#include "Poco/Exception.h"
+#include <iostream>
+
+
+using Poco::XML::SAXParser;
+using Poco::XML::XMLReader;
+using Poco::XML::WhitespaceFilter;
+using Poco::XML::InputSource;
+using Poco::XML::XMLWriter;
+using Poco::Exception;
+
+
+int main(int argc, char** argv)
+{
+	// read XML from standard input and pretty-print it to standard output
+
+	SAXParser parser;
+	WhitespaceFilter filter(&parser);
+	
+	XMLWriter writer(std::cout, XMLWriter::CANONICAL | XMLWriter::PRETTY_PRINT);
+	writer.setNewLine(XMLWriter::NEWLINE_LF);
+
+	filter.setContentHandler(&writer);
+	filter.setDTDHandler(&writer);
+	filter.setProperty(XMLReader::PROPERTY_LEXICAL_HANDLER, static_cast<Poco::XML::LexicalHandler*>(&writer));
+
+	try
+	{
+		InputSource source(std::cin);
+		filter.parse(&source);
+	}
+	catch (Exception& exc)
+	{
+		std::cerr << exc.displayText() << std::endl;
+		return 1;
+	}
+
+	return 0;
+}