Bug 124620 Referenced Parameter icon should be invalid if the parameter in library is deleted
Description: Referenced parameter icon should be invalid if the source parameter in library is deleted. Steps to reproduce: 1.Create a library. Insert a report scalar parameter. 2.Create a report, use the above library. In the library explorer, pull the parameter to the data explorer view of report. 3.Open the library file, delete the parameter. Then reopen the report design file, the icon of parameter seems nothing happened. But if those operations happened in dataset, the icon of dataset in the report will be invalid. It is acceptable. Expected Result: The icon of referenced parameter should be invalid.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/DesignElement.java
* reside in the {@link Module Module}.
 * <p>
 * An element also has a <em>display name</em> that is shown to the user. The
 * display name is optional, and is represented by a system property value. If
 * not provided, then the user sees the name. The display name is localizable.
 * Localized names are important for elements used in templates when the users
 * of the templates are international.
 * <p>
 * Members and classes in the name system include:
 * <p>
 * <ul>
 * <li>The {@link #setName}method.</li>
 * <li>The {@link #getName}method.</li>
 * <li>The {@link NameSpace NameSpace}class.</li>
 * </ul>
 * 
 * <h3>Containment</h3>
 * 
 * The overall report design organizes design elements into a hierarchy. All
 * elements except the report design itself are <em>contained </em> within some
 * other element: the <em>container </em>. The contained element is the
 * <em>content
 * </em>. (Note: the usage of the term container in this
 * discussion is more generic than the Container element in the report design.
 * The Container element is a container, but other elements are as well.)
 * <p>
 * The details of the containment are specific to each element type. For
 * example, a Container element has an ordered list of content elements. The
 * design has a named list of styles, and an ordered list of sections. As a
 * result, the implementation of the container-to-content relationship must be