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
*         reference a shared style, or the value is un-resolved
	 */
	public StyleElement getStyle( )
	{
		return null;
	}
	/**
	 * Caches an element that derives from this element.
	 * <p>
	 * Part of: Inheritance system.
	 * 
	 * @param child
	 *            The new derived element.
	 */
	protected void addDerived( DesignElement child )
	{
		if ( derived == null )
			derived = new ArrayList( );
		assert child != null;
		assert child.getExtendsElement( ) == this;
		assert !derived.contains( child );
		assert child.getDefn( ) == getDefn( );
		derived.add( child );
	}
	/**
	 * Removes a cached element that derives from this element.
	 * <p>
	 * Part of: Inheritance system.
	 * 
	 * @param child