Graph data structure classes.

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	Interface	Description
	IEdge	Interface for an edge in a graph.
	IGraph	Interface for a graph.
	IGraphItem	Interface for an item in a graph.
	INode	Interface for a node in a graph.

	Class	Description
	Edge	A directed edge in a graph.
	Graph	Stores graph data.
	GraphChangeType	Defines constants for types of changes to a dataset.
	GraphError	Thrown by graph classes.
	GraphEvent	An event associated with a graph.
	GraphItem	An item in a graph.
	GraphItemEvent	An event associated with a graph item.
	LinkedEdge	An edge in a linked graph.
	LinkedGraph	Stores graph data and maintains references between nodes and edges.
	LinkedNode	A node in a linked graph.
	Node	A class representing a node in a graph