Bug 213126 Add support for DataEngine-leve dataset cache
In many cases the DataEngine-leve dataset cache is useful which ensure that a dataset is executed one time during rendering one report. To support this feature a new dataset property should be added. The Birt customer can choose whether this dataset need to be cached or not by setting the property in deisgn time.
model/org.eclipse.birt.report.model.tests/test/org/eclipse/birt/report/model/parser/JointDataSetParseTest.java
* <td>The data set should be correctly saved into the output file.</td>
 * </tr>
 * 
 * <tr>
 * <td>testValidation</td>
 * <td>A report design file has six joint data sets, each one of which has a
 * blank field.</td>
 * <td>After the design file is parsed, six sematic errors should be returned.</td>
 * </tr>
 * 
 * <tr>
 * <td>testSemanticCheck</td>
 * <td>A joint data set refers to an unexist data set will create semantic
 * error.</td>
 * <td>A semantic error with invalid element reference error code will be
 * returned after reprot is parsed.</td>
 * </tr>
 * 
 * </table>
 * 
 * @see org.eclipse.birt.report.model.elements.JointDataSet
 */
public class JointDataSetParseTest extends BaseTestCase
{
	String inputFileName = "JointDataSetParseTest.xml"; 
	String outFileName = "JointDataSetParseTest_out.xml"; 
	String goldenFileName = "JointDataSetParseTest_golden.xml"; 
	String validationInputFileName = "JointDataSetParseTest_validation.xml"; 
	String semanticCheckFileName = "JointDataSetParseTest_semantic.xml"; 
	/**