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
conditionHandle.addItem( condition );
		save( );
		assertTrue( compareFile( goldenFileName ) );
	}
	/**
	 * If there is any blank field in the join condition, a semantic error
	 * should be returned by the parser.
	 * 
	 * In the input file, there are six joint data sets, each one of which has a
	 * blank field. So after the file is parsed, six semantic errors should be
	 * returned.
	 * 
	 * @throws Exception
	 *             design file exception
	 */
	public void testValidation( ) throws Exception
	{
		openDesign( validationInputFileName );
		List errors = designHandle.getErrorList( );
		assertEquals( 6, errors.size( ) );
		assertHasError( (ErrorDetail) errors.get( 0 ), "JointDataSet1" ); 
		assertHasError( (ErrorDetail) errors.get( 1 ), "JointDataSet2" ); 
		assertHasError( (ErrorDetail) errors.get( 2 ), "JointDataSet3" ); 
		assertHasError( (ErrorDetail) errors.get( 3 ), "JointDataSet4" ); 
		assertHasError( (ErrorDetail) errors.get( 4 ), "JointDataSet5" ); 
		assertHasError( (ErrorDetail) errors.get( 5 ), "JointDataSet6" ); 
	}
	/**
	 * Tests invalid reference to unexist data set will get semantic error.
	 *