Bug 200471 Add "need not sort for grouping" option in report item
Currently when Data engine proceeds groups, it always sorts the result set according to given group key.However that should not be necessary when the raw data is already sorted. So we'd like to add new options so that user can indicate whether should we sort the data before grouping. In model, we should allow user to set a "need not do sort for grouping" option to all the report element that can be grouped(table, list,etc.)
model/org.eclipse.birt.report.model.tests/test/org/eclipse/birt/report/model/parser/TableItemParseTest.java
* <tr>
 * <td></td>
 * <td>Test all properties of GroupFilter after parsing design file</td>
 * <td>GroupFilter is not implemented</td>
 * </tr>
 * 
 * <tr>
 * <td></td>
 * <td>Test all properties of TOC after parsing design file</td>
 * <td>TOC is not implemented</td>
 * </tr>
 * 
 * <tr>
 * <td>{@link #testWriter()}</td>
 * <td>Compare the written file with the golden file</td>
 * <td>Two files are same</td>
 * </tr>
 * 
 * <tr>
 * <td>{@link #testSemanticCheck()}</td>
 * <td>Test inconsistant column count error</td>
 * <td>Error found</td>
 * </tr>
 * 
 * <tr>
 * <td></td>
 * <td>Test cell overlapping error</td>
 * <td>Error found</td>
 * </tr>
 *