Bug 180118 Enhance to print out source stack trace in preview mode.[0002]
viewer/org.eclipse.birt.report.viewer/birt/WEB-INF/classes/org/eclipse/birt/report/servlet/ViewerServlet.java
* <ul>
 * <li>__report</li>
 * <li>__locale</li>
 * <li><i>report parameter</i></li>
 * </ul>
 * <li>Run
 * <ul>
 * <li>__report</li>
 * <li>__format</li>
 * <li>__locale</li>
 * <li>__page</li>
 * <li><i>report parameter</i></li>
 * </ul>
 * </ul>
 * <p>
 * Each URL parameter is described below. <table border=1>
 * <tr>
 * <td><b>Parameter</b></td>
 * <td><b>Description</b></td>
 * <td><b>Values</b></td>
 * <td><b>Default</b></td>
 * </tr>
 * <tr>
 * <td>__report</td>
 * <td>The path to the report document</td>
 * <td>&nbsp;</td>
 * <td>required</td>
 * </tr>
 * <tr>
 * <td>__format</td>