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
String propName = userProp.getName( );
		assert getUserPropertyDefn( propName ) == null;
		assert getDefn( ).getProperty( propName ) == null;
		if ( userProperties == null )
			userProperties = new LinkedHashMap( );
		userProperties.put( propName, userProp );
	}
	/**
	 * Drops a user-defined property. The application must have previously
	 * removed all existing values for that property. The application must have
	 * previously validated that the user-defined property does exist, and is
	 * defined on this element.
	 * <p>
	 * Part of: User-defined property system.
	 * 
	 * @param prop
	 *            The user-defined property.
	 */
	public void dropUserPropertyDefn( UserPropertyDefn prop )
	{
		assert getDefn( ).allowsUserProperties( );
		assert userProperties != null;
		assert userProperties.get( prop.getName( ) ) == prop;
		userProperties.remove( prop.getName( ) );
	}
	/**
	 * Gets a user property definition defined on this class itself.
	 * <p>
	 * Part of: User-defined property system.
	 *