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/elements/interfaces/IReportDesignModel.java
*/
	public static final String REFRESH_RATE_PROP = "refreshRate"; 
	/**
	 * Name of the method called at the start of the Factory after the
	 * initialize( ) method and before opening the report document (if any).
	 */
	public static final String BEFORE_FACTORY_METHOD = "beforeFactory"; 
	/**
	 * Name of the method called at the end of the Factory after closing the
	 * report document (if any). This is the last method called in the Factory.
	 */
	public static final String AFTER_FACTORY_METHOD = "afterFactory"; 
	/**
	 * Name of the method called before starting a presentation time action.
	 */
	public static final String BEFORE_RENDER_METHOD = "beforeRender"; 
	/**
	 * Name of the method called after starting a presentation time action.
	 */
	public static final String AFTER_RENDER_METHOD = "afterRender"; 
	
	/**
	 * Name of the property to store report design icon/thumbnail file path.
	 */
	
	public static final String ICON_FILE_PROP = "iconFile"; 
		
	/**
	 * Name of the property to store the cheet sheet file name.
	 */