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/Net/samples/download/src/download.cpp

@@ -0,0 +1,60 @@
+//
+// download.cpp
+//
+// This sample demonstrates the URIStreamOpener class.
+//
+// Copyright (c) 2005-2006, Applied Informatics Software Engineering GmbH.
+// and Contributors.
+//
+// SPDX-License-Identifier:	BSL-1.0
+//
+
+
+#include "Poco/URIStreamOpener.h"
+#include "Poco/StreamCopier.h"
+#include "Poco/Path.h"
+#include "Poco/URI.h"
+#include "Poco/Exception.h"
+#include "Poco/Net/HTTPStreamFactory.h"
+#include "Poco/Net/FTPStreamFactory.h"
+#include <memory>
+#include <iostream>
+
+
+using Poco::URIStreamOpener;
+using Poco::StreamCopier;
+using Poco::Path;
+using Poco::URI;
+using Poco::Exception;
+using Poco::Net::HTTPStreamFactory;
+using Poco::Net::FTPStreamFactory;
+
+
+int main(int argc, char** argv)
+{
+	HTTPStreamFactory::registerFactory();
+	FTPStreamFactory::registerFactory();
+
+	if (argc != 2)
+	{
+		Path p(argv[0]);
+		std::cerr << "usage: " << p.getBaseName() << " <uri>" << std::endl;
+		std::cerr << "       Download <uri> to standard output." << std::endl;
+		std::cerr << "       Works with http, ftp and file URIs." << std::endl;
+		return 1;
+	}
+
+	try
+	{
+		URI uri(argv[1]);
+		std::unique_ptr<std::istream> pStr(URIStreamOpener::defaultOpener().open(uri));
+		StreamCopier::copyStream(*pStr.get(), std::cout);
+	}
+	catch (Exception& exc)
+	{
+		std::cerr << exc.displayText() << std::endl;
+		return 1;
+	}
+
+	return 0;
+}