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/src/HTTPIOStream.cpp

@@ -0,0 +1,65 @@
+//
+// HTTPIOStream.cpp
+//
+// Library: Net
+// Package: HTTP
+// Module:  HTTPIOStream
+//
+// Copyright (c) 2005-2006, Applied Informatics Software Engineering GmbH.
+// and Contributors.
+//
+// SPDX-License-Identifier:	BSL-1.0
+//
+
+
+#include "Poco/Net/HTTPIOStream.h"
+#include "Poco/Net/HTTPClientSession.h"
+
+
+using Poco::UnbufferedStreamBuf;
+
+
+namespace Poco {
+namespace Net {
+
+
+HTTPResponseStreamBuf::HTTPResponseStreamBuf(std::istream& istr):
+	_istr(istr)
+{
+	// make sure exceptions from underlying string propagate
+	_istr.exceptions(std::ios::badbit);
+}
+
+
+HTTPResponseStreamBuf::~HTTPResponseStreamBuf()
+{
+}
+
+
+HTTPResponseIOS::HTTPResponseIOS(std::istream& istr):
+	_buf(istr)
+{
+	poco_ios_init(&_buf);
+}
+
+
+HTTPResponseIOS::~HTTPResponseIOS()
+{
+}
+
+
+HTTPResponseStream::HTTPResponseStream(std::istream& istr, HTTPClientSession* pSession):
+	HTTPResponseIOS(istr),
+	std::istream(&_buf),
+	_pSession(pSession)
+{
+}
+
+
+HTTPResponseStream::~HTTPResponseStream()
+{
+	delete _pSession;
+}
+
+
+} } // namespace Poco::Net