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/StreamConverter.h

@@ -0,0 +1,128 @@
+//
+// StreamConverter.h
+//
+// Library: Foundation
+// Package: Text
+// Module:  StreamConverter
+//
+// Definition of the StreamConverter class.
+//
+// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
+// and Contributors.
+//
+// SPDX-License-Identifier:	BSL-1.0
+//
+
+
+#ifndef Foundation_StreamConverter_INCLUDED
+#define Foundation_StreamConverter_INCLUDED
+
+
+#include "Poco/Foundation.h"
+#include "Poco/TextEncoding.h"
+#include "Poco/UnbufferedStreamBuf.h"
+#include <istream>
+#include <ostream>
+
+
+namespace Poco {
+
+
+class Foundation_API StreamConverterBuf: public UnbufferedStreamBuf
+	/// A StreamConverter converts streams from one encoding (inEncoding)
+	/// into another (outEncoding).
+	/// If a character cannot be represented in outEncoding, defaultChar
+	/// is used instead.
+	/// If a byte sequence is not valid in inEncoding, defaultChar is used
+	/// instead and the encoding error count is incremented.
+{
+public:
+	StreamConverterBuf(std::istream& istr, const TextEncoding& inEncoding, const TextEncoding& outEncoding, int defaultChar = '?');
+		/// Creates the StreamConverterBuf and connects it
+		/// to the given input stream.
+
+	StreamConverterBuf(std::ostream& ostr, const TextEncoding& inEncoding, const TextEncoding& outEncoding, int defaultChar = '?');
+		/// Creates the StreamConverterBuf and connects it
+		/// to the given output stream.
+
+	~StreamConverterBuf();
+		/// Destroys the StreamConverterBuf.
+
+	int errors() const;
+		/// Returns the number of encoding errors encountered.
+
+protected:
+	int readFromDevice();
+	int writeToDevice(char c);
+
+private:
+	std::istream*       _pIstr;
+	std::ostream*       _pOstr;
+	const TextEncoding& _inEncoding;
+	const TextEncoding& _outEncoding;
+	int                 _defaultChar;
+	unsigned char       _buffer[TextEncoding::MAX_SEQUENCE_LENGTH];
+	int                 _sequenceLength;
+	int                 _pos;
+	int                 _errors;
+};
+
+
+class Foundation_API StreamConverterIOS: public virtual std::ios
+	/// The base class for InputStreamConverter and OutputStreamConverter.
+	///
+	/// This class is needed to ensure the correct initialization
+	/// order of the stream buffer and base classes.
+{
+public:
+	StreamConverterIOS(std::istream& istr, const TextEncoding& inEncoding, const TextEncoding& outEncoding, int defaultChar = '?');
+	StreamConverterIOS(std::ostream& ostr, const TextEncoding& inEncoding, const TextEncoding& outEncoding, int defaultChar = '?');
+	~StreamConverterIOS();
+	StreamConverterBuf* rdbuf();
+	int errors() const;
+
+protected:
+	StreamConverterBuf _buf;
+};
+
+
+class Foundation_API InputStreamConverter: public StreamConverterIOS, public std::istream
+	/// This stream converts all characters read from the
+	/// underlying istream from one character encoding into another.
+	/// If a character cannot be represented in outEncoding, defaultChar
+	/// is used instead.
+	/// If a byte sequence read from the underlying stream is not valid in inEncoding, 
+	/// defaultChar is used instead and the encoding error count is incremented.
+{
+public:
+	InputStreamConverter(std::istream& istr, const TextEncoding& inEncoding, const TextEncoding& outEncoding, int defaultChar = '?');
+		/// Creates the InputStreamConverter and connects it
+		/// to the given input stream.
+
+	~InputStreamConverter();
+		/// Destroys the stream.
+};
+
+
+class Foundation_API OutputStreamConverter: public StreamConverterIOS, public std::ostream
+	/// This stream converts all characters written to the
+	/// underlying ostream from one character encoding into another.
+	/// If a character cannot be represented in outEncoding, defaultChar
+	/// is used instead.
+	/// If a byte sequence written to the stream is not valid in inEncoding, 
+	/// defaultChar is used instead and the encoding error count is incremented.
+{
+public:
+	OutputStreamConverter(std::ostream& ostr, const TextEncoding& inEncoding, const TextEncoding& outEncoding, int defaultChar = '?');
+		/// Creates the OutputStreamConverter and connects it
+		/// to the given input stream.
+
+	~OutputStreamConverter();
+		/// Destroys the CountingOutputStream.
+};
+
+
+} // namespace Poco
+
+
+#endif // Foundation_StreamConverter_INCLUDED