Bug 130492 Provide a method to serialize the report with library information.
Currently, when engine generate the report document file, the document does not contain any library information. That will cause many propblem on server side. Model should provide a method to serialize the report with library information to a stream so that the generated report document can contain all information that the report need.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/ReferencableStructure.java
* Adds a client structure of this.
	 * 
	 * @param struct
	 *            the structure that refers this struct
	 */
	public void addClientStructure( Structure struct )
	{
		clientStructures.add( struct );
	}
	/**
	 * Drops one of the client of this structure.
	 * 
	 * @param struct
	 *            the client to drop
	 */
	public void dropClientStructure( Structure struct )
	{
		assert clientStructures.contains( struct );
		clientStructures.remove( struct );
	}
	/**
	 * Returns all the client structures.
	 * 
	 * @return all the client structures
	 */
	public List getClientStructures( )
	{
		return clientStructures;
	}
}