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
* context, system-defaults, and other information. The effective value is
 * generally what the user cares about, and is what appears in the property
 * sheet and other UI.
 * <p>
 * Members and classes in the property value system include:
 * <p>
 * <ul>
 * <li>The {@link #propValues}member stores the property values set on this
 * element.</li>
 * <li>The {@link #setProperty( String, Object )}method sets a property value
 * on this element.</li>
 * <li>The {@link #clearProperty}method unsets a property value on this
 * method.</li>
 * <li>The {@link #getLocalProperty( Module, String )}method gets the property
 * value, if any, set on this element.</li>
 * <li>The {@link #getProperty( Module, String )}method gets the effective
 * value of the property.</li>
 * </ul>
 * 
 * <h3>Element Name</h3>
 * 
 * Elements can have a name. The semantics of the specific element type
 * determine if the element name is optional or required. In a few contexts, the
 * name may be ignored (not supported). The name uniquely identifies an element
 * and is locale-independent. (The display name, described below, is
 * localizable.) Elements with a name can be referenced in the design or in
 * code. Elements without a name can be referenced in code by navigating to the
 * element.
 * <p>
 * If an element has a name, then it resides in a name space. All name spaces