Bug 150347 Support binary stream as preview image.
See 144843. We need model to save binary strame as report preview image. Currently, preview image is an external image. Maybe need a type to distinguish preview image type.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/ReportDesignHandle.java
* Returns the script called at the end of the Factory after closing the
	 * report document (if any). This is the last method called in the Factory.
	 * 
	 * @return the script
	 */
	public String getAfterFactory( )
	{
		return getStringProperty( AFTER_FACTORY_METHOD );
	}
	/**
	 * Returns the script called after starting a presentation time action.
	 * 
	 * @return the script
	 */
	public String getAfterRender( )
	{
		return getStringProperty( AFTER_RENDER_METHOD );
	}
	/**
	 * Returns the base directory to use when computing relative links from this
	 * report. Especially used for searching images, library and so.
	 * 
	 * @return the base directory
	 */
	public String getBase( )
	{
		return module.getStringProperty( module, BASE_PROP );
	}
	/**
	 * Returns the script called at the start of the Factory after the