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/NetSSL_OpenSSL/include/Poco/Net/KeyFileHandler.h

@@ -0,0 +1,51 @@
+//
+// KeyFileHandler.h
+//
+// Library: NetSSL_OpenSSL
+// Package: SSLCore
+// Module:  KeyFileHandler
+//
+// Definition of the KeyFileHandler class.
+//
+// Copyright (c) 2006-2009, Applied Informatics Software Engineering GmbH.
+// and Contributors.
+//
+// SPDX-License-Identifier:	BSL-1.0
+//
+
+
+#ifndef NetSSL_KeyFileHandler_INCLUDED
+#define NetSSL_KeyFileHandler_INCLUDED
+
+
+#include "Poco/Net/NetSSL.h"
+#include "Poco/Net/PrivateKeyPassphraseHandler.h"
+
+
+namespace Poco {
+namespace Net {
+
+
+class NetSSL_API KeyFileHandler: public PrivateKeyPassphraseHandler
+	/// An implementation of PrivateKeyPassphraseHandler that 
+	/// reads the key for a certificate from a configuration file
+	/// under the path "openSSL.privateKeyPassphraseHandler.options.password".
+{
+public:
+	KeyFileHandler(bool server);
+		/// Creates the KeyFileHandler.
+
+	virtual ~KeyFileHandler();
+		/// Destroys the KeyFileHandler.
+
+	void onPrivateKeyRequested(const void* pSender, std::string& privateKey);
+
+private:
+	static const std::string CFG_PRIV_KEY_FILE;
+};
+
+
+} } // namespace Poco::Net
+
+
+#endif // NetSSL_KeyFileHandler_INCLUDED