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/hmacmd5/src/hmacmd5.cpp

@@ -0,0 +1,55 @@
+//
+// hmacmd5.cpp
+//
+// This sample demonstrates the HMACEngine class.
+//
+// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
+// and Contributors.
+//
+// SPDX-License-Identifier:	BSL-1.0
+//
+
+
+#include "Poco/HMACEngine.h"
+#include "Poco/MD5Engine.h"
+#include "Poco/DigestStream.h"
+#include "Poco/StreamCopier.h"
+#include <fstream>
+#include <iostream>
+
+
+using Poco::DigestEngine;
+using Poco::HMACEngine;
+using Poco::MD5Engine;
+using Poco::DigestOutputStream;
+using Poco::StreamCopier;
+
+
+int main(int argc, char** argv)
+{
+	if (argc != 3)
+	{
+		std::cout << "usage: " << argv[0] << ": <passphrase> <input_file>" << std::endl
+		          << "       create the HMAC-MD5 for <input_file>, using <passphrase>" << std::endl;
+		return 1;
+	}
+	
+	std::string passphrase(argv[1]);
+	
+	std::ifstream istr(argv[2], std::ios::binary);
+	if (!istr)
+	{
+		std::cerr << "cannot open input file: " << argv[2] << std::endl;
+		return 2;
+	}
+	
+	HMACEngine<MD5Engine> hmac(passphrase);
+	DigestOutputStream dos(hmac);
+	
+	StreamCopier::copyStream(istr, dos);
+	dos.close();
+	
+	std::cout << DigestEngine::digestToHex(hmac.digest()) << std::endl;
+	
+	return 0;
+}