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/UTF32Encoding.h

@@ -0,0 +1,82 @@
+//
+// UTF32Encoding.h
+//
+// Library: Foundation
+// Package: Text
+// Module:  UTF32Encoding
+//
+// Definition of the UTF32Encoding class.
+//
+// Copyright (c) 2004-2007, Applied Informatics Software Engineering GmbH.
+// and Contributors.
+//
+// SPDX-License-Identifier:	BSL-1.0
+//
+
+
+#ifndef Foundation_UTF32Encoding_INCLUDED
+#define Foundation_UTF32Encoding_INCLUDED
+
+
+#include "Poco/Foundation.h"
+#include "Poco/TextEncoding.h"
+
+
+namespace Poco {
+
+
+class Foundation_API UTF32Encoding: public TextEncoding
+	/// UTF-32 text encoding, as defined in RFC 2781.
+	///
+	/// When converting from UTF-32 to Unicode, surrogates are
+	/// reported as they are - in other words, surrogate pairs
+	/// are not combined into one Unicode character. 
+{
+public:
+	enum ByteOrderType
+	{
+		BIG_ENDIAN_BYTE_ORDER,
+		LITTLE_ENDIAN_BYTE_ORDER,
+		NATIVE_BYTE_ORDER
+	};
+	
+	UTF32Encoding(ByteOrderType byteOrder = NATIVE_BYTE_ORDER);
+		/// Creates and initializes the encoding for the given byte order.
+		
+	UTF32Encoding(int byteOrderMark);
+		/// Creates and initializes the encoding for the byte-order
+		/// indicated by the given byte-order mark, which is the Unicode
+		/// character 0xFEFF.
+		
+	~UTF32Encoding();
+	
+	ByteOrderType getByteOrder() const;
+		/// Returns the byte-order currently in use.
+		
+	void setByteOrder(ByteOrderType byteOrder);
+		/// Sets the byte order.
+		
+	void setByteOrder(int byteOrderMark);
+		/// Sets the byte order according to the given
+		/// byte order mark, which is the Unicode
+		/// character 0xFEFF.
+	
+	const char* canonicalName() const;
+	bool isA(const std::string& encodingName) const;
+	const CharacterMap& characterMap() const;
+	int convert(const unsigned char* bytes) const;
+	int convert(int ch, unsigned char* bytes, int length) const;
+	int queryConvert(const unsigned char* bytes, int length) const;
+	int sequenceLength(const unsigned char* bytes, int length) const;
+	
+private:
+	bool _flipBytes;
+	static const char* _names[];
+	static const CharacterMap _charMap;
+};
+
+
+} // namespace Poco
+
+
+#endif // Foundation_UTF32Encoding_INCLUDED