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
* <ul>
 * <li>The {@link #setExtendsElement}method sets the parent element.</li>
 * <li>The {@link #setExtendsName}method sets the name of the parent element.
 * It is used when reading a design file, or if it is necessary to store an
 * unresolved parent name.</li>
 * <li>The {@link #getExtendsElement}method gets the parent element.</li>
 * <li>The {@link #extendsRef}member stores the reference to the parent
 * element.</li>
 * </ul>
 * 
 * <h3>User-Defined Properties</h3>
 * 
 * As noted above, the user can define user-defined properties for an element.
 * User-defined properties have many of the same attributes as system-defined
 * properties. User-defined properties work virtually the same as system-defined
 * properties, including support for localization, for a property type, for
 * validating the property value, and more.
 * <p>
 * Members and classes in the user-defined property system include:
 * <p>
 * <ul>
 * <li>The {@link #addUserPropertyDefn}method defines a user-defined property.
 * </li>
 * <li>The {@link #dropUserPropertyDefn}method removes a user-defined
 * property.</li>
 * <li>The {@link #getUserPropertyDefn}method gets the definition of a
 * user-defined property.</li>
 * <li>The {@link UserPropertyDefn}class defines a user-defined property.
 * </li>
 * <li>The {@link #userProperties}member holds the user-defined property