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
* change.
	 */
	protected IElementDefn cachedDefn = null;
	/**
	 * Indicates whether the element is valid. The initial value is true.
	 */
	protected boolean isValid = true;
	/**
	 * API handle for this element.
	 */
	protected DesignElementHandle handle = null;
	/**
	 * The validation error list, each of which is the instance of
	 * <code>SemanticException</code>.
	 */
	protected List errors;
	/**
	 * Constant indicate that the element has no virtual parent.
	 */
	public final static long NO_BASE_ID = -1;
	/**
	 * Constant indicate that the element has no id.
	 */
	public final static long NO_ID = 0;
	/**
	 * Support for id inheritance. If it is set, base id must be larger than
	 * <code>0</code>.
	 */
	protected long baseId = NO_BASE_ID;
	/**