Bug 211703 Support muti-view on report item.
As title described.
xtab/org.eclipse.birt.report.item.crosstab.core/src/org/eclipse/birt/report/item/crosstab/core/ICrosstabReportItemConstants.java
String HIDE_MEASURE_HEADER_PROP = "hideMeasureHeader"; 
	/**
	 * Name of the property that gives the value shown when the cell is empty in
	 * the crosstab.
	 */
	String EMPTY_CELL_VALUE_PROP = "emptyCellValue"; 
	/**
	 * Name of the property that contains a list of MeasureView elements.
	 */
	String MEASURES_PROP = "measures"; 
	/**
	 * Name of the property that contains single CrosstabView for row axis.
	 */
	String ROWS_PROP = "rows"; 
	/**
	 * Name of the property that contains single CrosstabView for column axis.
	 */
	String COLUMNS_PROP = "columns"; 
	/**
	 * Name of the property that contains the crosstab header cell.
	 * 
	 * @since 2.3
	 */
	String HEADER_PROP = "header"; 
	/**
	 * Name of the property that contains single MultiViews.
	 */
	String MULTI_VIEWS_PROP = "multiViews"; 
}