Bug 179674 Support time dimension in model
When define time dimension in model, the "itTime" property will be set. However this is not enough. We also need to know to what precision the time value should be evaluated, say, year, month, day, etc. Model needs to be enhanced to support such requirement.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/writer/ModuleWriter.java
List properties = (List) obj.getLocalProperty( getModule( ),
				IOdaDataSetModel.PRIVATE_DRIVER_PROPERTIES_PROP );
		writeExtendedProperties( properties,
				IOdaDataSetModel.PRIVATE_DRIVER_PROPERTIES_PROP );
		writeOdaExtensionProperties( obj,
				IOdaExtendableElementModel.EXTENSION_ID_PROP );
		writer.endElement( );
	}
	/**
	 * Writes the columns slot of <code>GridItem</code> and
	 * <code>TableItem</code>.
	 * 
	 * @param obj
	 *            the grid item or table item
	 * @param slot
	 *            the columns slot
	 */
	private void writeColumns( DesignElement obj, int slot )
	{
		assert obj instanceof GridItem || obj instanceof TableItem;
		assert slot == IGridItemModel.COLUMN_SLOT
				|| slot == ITableItemModel.COLUMN_SLOT;
		
		
		
		boolean revert = true;
		if ( revert )
		{
			writeContents( obj, slot, null );
			return;