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/DesignElement.java
*            the display label to be elided.
	 * @return the elided display label.
	 */
	protected String limitStringLength( String displayLabel )
	{
		if ( displayLabel == null )
			return null;
		if ( displayLabel.length( ) > MAX_DISPLAY_LABEL_LEN )
		{
			displayLabel = displayLabel.substring( 0, MAX_DISPLAY_LABEL_LEN );
			int pos = displayLabel.lastIndexOf( " " ); 
			if ( pos != -1 )
			{
				displayLabel = displayLabel.substring( 0, pos );
			}
			return displayLabel + "..."; 
		}
		return displayLabel;
	}
	/**
	 * Generates a clone copy of this element. When a report element is cloned,
	 * the basic principle is just copying the property value into the clone,
	 * the other things, like container references, child list references,
	 * listener references will not be cloned; that is, the clone is isolated
	 * from the design tree until it is added into a target design tree.
	 * 
	 * <p>
	 * When inserting the cloned element into the design tree, user needs to
	 * care about the element name confliction; that is, the client needs to
	 * call the method