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/base64encode/src/base64encode.cpp

@@ -0,0 +1,56 @@
+//
+// base64encode.cpp
+//
+// This sample demonstrates the Base64Encoder and StreamCopier classes.
+//
+// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
+// and Contributors.
+//
+// SPDX-License-Identifier:	BSL-1.0
+//
+
+
+#include "Poco/Base64Encoder.h"
+#include "Poco/StreamCopier.h"
+#include <iostream>
+#include <fstream>
+
+
+using Poco::Base64Encoder;
+using Poco::StreamCopier;
+
+
+int main(int argc, char** argv)
+{
+	if (argc != 3)
+	{
+		std::cout << "usage: " << argv[0] << ": <input_file> <output_file>" << std::endl
+		          << "       read <input_file>, base64-encode it and write the result to <output_file>" << std::endl;
+		return 1;
+	}
+	
+	std::ifstream istr(argv[1], std::ios::binary);
+	if (!istr)
+	{
+		std::cerr << "cannot open input file: " << argv[1] << std::endl;
+		return 2;
+	}
+	
+	std::ofstream ostr(argv[2]);
+	if (!ostr)
+	{
+		std::cerr << "cannot open output file: " << argv[2] << std::endl;
+		return 3;
+	}
+	
+	Base64Encoder encoder(ostr);
+	StreamCopier::copyStream(istr, encoder);
+	
+	if (!ostr)
+	{
+		std::cerr << "error writing output file: " << argv[2] << std::endl;
+		return 4;
+	}
+	
+	return 0;
+}