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
* <td>Reusable report items defined in this design. Report items can extend
 * these items. Defines a "private library" for this design.</td>
 * </tr>
 * 
 * <tr>
 * <td>Body</td>
 * <td>A list of the visual report content. Content is made up of one or more
 * sections. A section is a report item that fills the width of the page. It can
 * contain Text, Grid, List, Table, etc. elements</td>
 * </tr>
 * 
 * <tr>
 * <td>Scratch Pad</td>
 * <td>Temporary place to move report items while restructuring a report.</td>
 * </tr>
 * 
 * <tr>
 * <td>Translations</td>
 * <td>The list of externalized messages specifically for this report.</td>
 * </tr>
 * 
 * <tr>
 * <td>Images</td>
 * <td>A list of images embedded in this report.</td>
 * </tr>
 * 
 * </table>
 * 
 * <p>
 * Module allow to use the components defined in <code>Library</code>.