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/include/Poco/UnbufferedStreamBuf.h

@@ -0,0 +1,179 @@
+//
+// UnufferedStreamBuf.h
+//
+// Library: Foundation
+// Package: Streams
+// Module:  StreamBuf
+//
+// Definition of template BasicUnbufferedStreamBuf and class UnbufferedStreamBuf.
+//
+// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
+// and Contributors.
+//
+// SPDX-License-Identifier:	BSL-1.0
+//
+
+
+#ifndef Foundation_UnbufferedStreamBuf_INCLUDED
+#define Foundation_UnbufferedStreamBuf_INCLUDED
+
+
+#include "Poco/Foundation.h"
+#include "Poco/StreamUtil.h"
+#include <streambuf>
+#include <iosfwd>
+#include <ios>
+
+
+namespace Poco {
+
+
+template <typename ch, typename tr> 
+class BasicUnbufferedStreamBuf: public std::basic_streambuf<ch, tr>
+	/// This is an implementation of an unbuffered streambuf
+	/// that greatly simplifies the implementation of
+	/// custom streambufs of various kinds.
+	/// Derived classes only have to override the methods
+	/// readFromDevice() or writeToDevice().
+{
+protected:
+	typedef std::basic_streambuf<ch, tr> Base;
+	typedef std::basic_ios<ch, tr> IOS;
+	typedef ch char_type;
+	typedef tr char_traits;
+	typedef typename Base::int_type int_type;
+	typedef typename Base::pos_type pos_type;
+	typedef typename Base::off_type off_type;
+	typedef typename IOS::openmode openmode;
+
+public:
+	BasicUnbufferedStreamBuf():
+		_pb(char_traits::eof()),
+		_ispb(false)
+	{
+		this->setg(0, 0, 0);
+		this->setp(0, 0);
+	}
+
+	~BasicUnbufferedStreamBuf()
+	{
+	}
+
+	virtual int_type overflow(int_type c)
+	{
+		if (c != char_traits::eof()) 
+			return writeToDevice(char_traits::to_char_type(c));
+		else
+			return c;
+	}
+
+	virtual int_type underflow()
+	{
+		if (_ispb)
+		{
+			return _pb;
+		}
+		else
+		{
+			int_type c = readFromDevice();
+			if (c != char_traits::eof())
+			{
+				_ispb = true;
+				_pb   = c;
+			}
+			return c;
+		}
+	}
+
+	virtual int_type uflow()
+	{
+		if (_ispb)
+		{
+			_ispb = false;
+			return _pb;
+		}
+		else
+		{
+			int_type c = readFromDevice();
+			if (c != char_traits::eof())
+			{
+				_pb = c;
+			}
+			return c;
+		}
+	}
+
+	virtual int_type pbackfail(int_type c)
+	{
+		if (_ispb)
+		{
+			return char_traits::eof();
+		}
+		else
+		{
+			_ispb = true;
+			_pb   = c;
+			return c;
+		}
+	}
+	
+	virtual std::streamsize xsgetn(char_type* p, std::streamsize count)
+		/// Some platforms (for example, Compaq C++) have buggy implementations of 
+		/// xsgetn that handle null buffers incorrectly.
+		/// Anyway, it does not hurt to provide an optimized implementation
+		/// of xsgetn for this streambuf implementation.
+	{
+		std::streamsize copied = 0;
+		while (count > 0)
+		{
+			int_type c = uflow();
+			if (c == char_traits::eof()) break;
+			*p++ = char_traits::to_char_type(c);
+			++copied;
+			--count;
+		}
+		return copied;
+	}
+
+protected:
+	static int_type charToInt(char_type c)
+	{
+		return char_traits::to_int_type(c);
+	}
+
+private:
+	virtual int_type readFromDevice()
+	{
+		return char_traits::eof();
+	}
+	
+	virtual int_type writeToDevice(char_type)
+	{
+		return char_traits::eof();
+	}
+
+	int_type _pb;
+	bool     _ispb;
+	
+	BasicUnbufferedStreamBuf(const BasicUnbufferedStreamBuf&);
+	BasicUnbufferedStreamBuf& operator = (const BasicUnbufferedStreamBuf&);
+};
+
+
+//
+// We provide an instantiation for char.
+//
+// Visual C++ needs a workaround - explicitly importing the template
+// instantiation - to avoid duplicate symbols due to multiple
+// instantiations in different libraries.
+//
+#if defined(_MSC_VER) && defined(POCO_DLL) && !defined(Foundation_EXPORTS)
+template class Foundation_API BasicUnbufferedStreamBuf<char, std::char_traits<char>>;
+#endif
+typedef BasicUnbufferedStreamBuf<char, std::char_traits<char>> UnbufferedStreamBuf;
+
+
+} // namespace Poco
+
+
+#endif // Foundation_UnbufferedStreamBuf_INCLUDED