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/src/org/eclipse/birt/report/model/writer/ModuleWriter.java
* Writers the content node out to the file.
	 * 
	 * @param node
	 *            the content node to write out
	 */
	private void writeContentNode( ContentNode node )
	{
		String tagName = node.getName( );
		boolean isCdata = node.isCDATASection( );
		writer.startElement( tagName );
		
		Map attributes = node.getAttributes( );
		Iterator keys = attributes.keySet( ).iterator( );
		while ( keys.hasNext( ) )
		{
			String key = (String) keys.next( );
			String attr = (String) attributes.get( key );
			writer.attribute( key, attr );
		}
		
		String value = node.getValue( );
		List children = node.getChildren( );
		assert StringUtil.isBlank( value ) || children.isEmpty( );
		if ( !StringUtil.isBlank( value ) )
		{
			if ( isCdata )
				writer.textCDATA( value );
			else
				writer.text( value );
		}