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/testsuite/src/EchoServer.cpp

@@ -0,0 +1,82 @@
+//
+// EchoServer.cpp
+//
+// Copyright (c) 2005-2006, Applied Informatics Software Engineering GmbH.
+// and Contributors.
+//
+// SPDX-License-Identifier:	BSL-1.0
+//
+
+
+#include "EchoServer.h"
+#include "Poco/Net/StreamSocket.h"
+#include "Poco/Net/SocketAddress.h"
+#include "Poco/Timespan.h"
+#include <iostream>
+
+
+using Poco::Net::Socket;
+using Poco::Net::StreamSocket;
+using Poco::Net::SocketAddress;
+
+
+EchoServer::EchoServer():
+	_socket(SocketAddress()),
+	_thread("EchoServer"),
+	_stop(false)
+{
+	_thread.start(*this);
+	_ready.wait();
+}
+
+
+EchoServer::EchoServer(const Poco::Net::SocketAddress& address):
+	_socket(address),
+	_thread("EchoServer"),
+	_stop(false)
+{
+	_thread.start(*this);
+	_ready.wait();
+}
+
+
+EchoServer::~EchoServer()
+{
+	_stop = true;
+	_thread.join();
+}
+
+
+Poco::UInt16 EchoServer::port() const
+{
+	return _socket.address().port();
+}
+
+
+void EchoServer::run()
+{
+	_ready.set();
+	Poco::Timespan span(250000);
+	while (!_stop)
+	{
+		if (_socket.poll(span, Socket::SELECT_READ))
+		{
+			StreamSocket ss = _socket.acceptConnection();
+			try
+			{
+				char buffer[256];
+				int n = ss.receiveBytes(buffer, sizeof(buffer));
+				while (n > 0 && !_stop)
+				{
+					ss.sendBytes(buffer, n);
+					n = ss.receiveBytes(buffer, sizeof(buffer));
+				}
+			}
+			catch (Poco::Exception& exc)
+			{
+				std::cerr << "EchoServer: " << exc.displayText() << std::endl;
+			}
+		}
+	}
+}
+