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/XML/include/Poco/SAX/DeclHandler.h

@@ -0,0 +1,91 @@
+//
+// DeclHandler.h
+//
+// Library: XML
+// Package: SAX
+// Module:  SAX
+//
+// SAX2-ext DeclHandler Interface.
+//
+// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
+// and Contributors.
+//
+// SPDX-License-Identifier:	BSL-1.0
+//
+
+
+#ifndef SAX_DeclHandler_INCLUDED
+#define SAX_DeclHandler_INCLUDED
+
+
+#include "Poco/XML/XML.h"
+#include "Poco/XML/XMLString.h"
+
+
+namespace Poco {
+namespace XML {
+
+
+class XML_API DeclHandler
+	/// This is an optional extension handler for SAX2 to provide information 
+	/// about DTD declarations in an XML document. XML
+	/// readers are not required to support this handler, and this handler is 
+	/// not included in the core SAX2 distribution.
+	///
+	/// Note that data-related DTD declarations (unparsed entities and notations) 
+	/// are already reported through the DTDHandler interface.
+	/// If you are using the declaration handler together with a lexical handler, 
+	/// all of the events will occur between the startDTD and the endDTD events.
+	/// To set the DeclHandler for an XML reader, use the setProperty method 
+	/// with the propertyId "http://xml.org/sax/properties/declaration-handler". 
+	/// If the reader does not support declaration events, it will throw a
+	/// SAXNotRecognizedException or a SAXNotSupportedException when you attempt to 
+	/// register the handler.
+{
+public:
+	virtual void attributeDecl(const XMLString& eName, const XMLString& aName, const XMLString* valueDefault, const XMLString* value) = 0;
+		/// Report an attribute type declaration.
+		/// 
+		/// Only the effective (first) declaration for an attribute will be reported. 
+		/// The type will be one of the strings "CDATA", "ID", "IDREF", "IDREFS", 
+		/// "NMTOKEN", "NMTOKENS", "ENTITY", "ENTITIES", a parenthesized token group 
+		/// with the separator "|" and all whitespace removed, or the word "NOTATION" 
+		/// followed by a space followed by a parenthesized token group with all whitespace 
+		/// removed.
+		///
+		/// The value will be the value as reported to applications, appropriately normalized 
+		/// and with entity and character references expanded. 
+		
+	virtual void elementDecl(const XMLString& name, const XMLString& model) = 0;
+		/// Report an element type declaration.
+		///
+		/// The content model will consist of the string "EMPTY", the string "ANY", or a 
+		/// parenthesised group, optionally followed by an occurrence indicator. The model 
+		/// will be normalized so that all parameter entities are fully resolved and all 
+		/// whitespace is removed,and will include the enclosing parentheses. Other 
+		/// normalization (such as removing redundant parentheses or simplifying occurrence 
+		/// indicators) is at the discretion of the parser.
+		
+	virtual void externalEntityDecl(const XMLString& name, const XMLString* publicId, const XMLString& systemId) = 0;
+		/// Report an external entity declaration.
+		/// 
+		/// Only the effective (first) declaration for each entity will be reported.
+		/// 
+		/// If the system identifier is a URL, the parser must resolve it fully before 
+		/// passing it to the application.
+
+	virtual void internalEntityDecl(const XMLString& name, const XMLString& value) = 0;
+		/// Report an internal entity declaration.
+		///
+		/// Only the effective (first) declaration for each entity will be reported. All 
+		/// parameter entities in the value will be expanded, but general entities will not.
+
+protected:
+	virtual ~DeclHandler();
+};
+
+
+} } // namespace Poco::XML
+
+
+#endif // SAX_DeclHandler_INCLUDED