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/EntityResolverImpl.h

@@ -0,0 +1,78 @@
+//
+// EntityResolverImpl.h
+//
+// Library: XML
+// Package: SAX
+// Module:  SAX
+//
+// An implementation of EntityResolver.
+//
+// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
+// and Contributors.
+//
+// SPDX-License-Identifier:	BSL-1.0
+//
+
+
+#ifndef SAX_EntityResolverImpl_INCLUDED
+#define SAX_EntityResolverImpl_INCLUDED
+
+
+#include "Poco/XML/XML.h"
+#include "Poco/XML/XMLString.h"
+#include "Poco/SAX/EntityResolver.h"
+#include "Poco/URIStreamOpener.h"
+
+
+namespace Poco {
+namespace XML {
+
+
+class XML_API EntityResolverImpl: public EntityResolver
+	/// A default implementation of the EntityResolver interface.
+	///
+	/// The system ID is first interpreted as an URI and the
+	/// URIStreamOpener is used to create and open an istream
+	/// for an InputSource.
+	///
+	/// If the system ID is not a valid URI, it is
+	/// interpreted as a filesystem path and a Poco::FileInputStream
+	/// is opened for it.
+{
+public:
+	EntityResolverImpl();
+		/// Creates an EntityResolverImpl that uses the default
+		/// URIStreamOpener.
+		
+	EntityResolverImpl(const Poco::URIStreamOpener& opener);
+		/// Creates an EntityResolverImpl that uses the given
+		/// URIStreamOpener.
+		
+	~EntityResolverImpl();
+		/// Destroys the EntityResolverImpl.
+	
+	InputSource* resolveEntity(const XMLString* publicId, const XMLString& systemId);
+		/// Tries to use the URIStreamOpener to create and open an istream
+		/// for the given systemId, which is interpreted as an URI.
+		///
+		/// If the systemId is not a valid URI, it is interpreted as
+		/// a local filesystem path and a Poco::FileInputStream is opened for it.
+		
+	void releaseInputSource(InputSource* pSource);
+		/// Deletes the InputSource's stream.
+	
+protected:
+	std::istream* resolveSystemId(const XMLString& systemId);	
+	
+private:
+	EntityResolverImpl(const EntityResolverImpl&);
+	EntityResolverImpl& operator = (const EntityResolverImpl&);
+	
+	const Poco::URIStreamOpener& _opener;
+};
+
+
+} } // namespace Poco::XML
+
+
+#endif // SAX_EntityResolverImpl_INCLUDED