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/Dynamic/VarIterator.h

@@ -0,0 +1,155 @@
+//
+// VarIterator.h
+//
+// Library: Foundation
+// Package: Dynamic
+// Module:  VarIterator
+//
+// Definition of the VarIterator class.
+//
+// Copyright (c) 2006, Applied Informatics Software Engineering GmbH.
+// and Contributors.
+//
+// SPDX-License-Identifier:	BSL-1.0
+//
+
+
+#ifndef Foundation_VarIterator_INCLUDED
+#define Foundation_VarIterator_INCLUDED
+
+
+#include "Poco/Exception.h"
+#include <iterator>
+#include <algorithm>
+
+
+namespace Poco {
+namespace Dynamic {
+
+
+class Var;
+
+
+class Foundation_API VarIterator
+	/// VarIterator class.
+{
+public:
+	typedef std::bidirectional_iterator_tag iterator_category;
+	typedef Var                             value_type;
+	typedef std::ptrdiff_t                  difference_type;
+	typedef Var*                            pointer;
+	typedef Var&                            reference;
+
+	static const std::size_t POSITION_END;
+		/// End position indicator.
+
+	VarIterator(Var* pVar, bool positionEnd);
+		/// Creates the VarIterator and positions it at the end of
+		/// the recordset if positionEnd is true. Otherwise, it is
+		/// positioned at the beginning.
+
+	VarIterator(const VarIterator& other);
+		/// Creates a copy of other VarIterator.
+
+	VarIterator(VarIterator&& other) noexcept;
+		/// Moves another VarIterator.
+
+	~VarIterator();
+		/// Destroys the VarIterator.
+
+	VarIterator& operator = (const VarIterator& other);
+		/// Assigns the other VarIterator.
+
+	VarIterator& operator = (VarIterator&& other) noexcept;
+		/// Assigns the other VarIterator.
+
+	bool operator == (const VarIterator& other) const;
+		/// Equality operator.
+
+	bool operator != (const VarIterator& other) const;
+		/// Inequality operator.
+
+	Var& operator * () const;
+		/// Returns value at the current position.
+
+	Var* operator -> () const;
+		/// Returns pointer to the value at current position.
+
+	const VarIterator& operator ++ () const;
+		/// Advances by one position and returns current position.
+
+	VarIterator operator ++ (int) const;
+		/// Advances by one position and returns copy of the iterator with 
+		/// previous current position.
+
+	const VarIterator& operator -- () const;
+		/// Goes back by one position and returns copy of the iterator with 
+		/// previous current position.
+
+	VarIterator operator -- (int) const;
+		/// Goes back by one position and returns previous current position.
+
+	VarIterator operator + (std::size_t diff) const;
+		/// Returns a copy the VarIterator advanced by diff positions.
+
+	VarIterator operator - (std::size_t diff) const;
+		/// Returns a copy the VarIterator backed by diff positions.
+		/// Throws RangeException if diff is larger than current position.
+
+	void swap(VarIterator& other);
+		/// Swaps the VarIterator with another one.
+
+private:
+	VarIterator();
+
+	void increment() const;
+		/// Increments the iterator position by one. 
+		/// Throws RangeException if position is out of range.
+
+	void decrement() const;
+		/// Decrements the iterator position by one. 
+		/// Throws RangeException if position is out of range.
+
+	void setPosition(std::size_t pos) const;
+		/// Sets the iterator position. 
+		/// Throws RangeException if position is out of range.
+
+	Var*                _pVar;
+	mutable std::size_t _position;
+
+	friend class Var;
+};
+
+
+///
+/// inlines
+///
+
+
+inline bool VarIterator::operator == (const VarIterator& other) const
+{
+	return _pVar == other._pVar && _position == other._position;
+}
+
+
+inline bool VarIterator::operator != (const VarIterator& other) const
+{
+	return _pVar != other._pVar || _position != other._position;
+}
+
+
+} } // namespace Poco::Dynamic
+
+
+namespace std
+{
+	template<>
+	inline void swap<Poco::Dynamic::VarIterator>(Poco::Dynamic::VarIterator& s1, Poco::Dynamic::VarIterator& s2) noexcept
+		/// Full template specialization of std:::swap for VarIterator
+	{
+		s1.swap(s2);
+	}
+}
+
+
+#endif // Foundation_VarIterator_INCLUDED