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
writeContents( obj, ISimpleMasterPageModel.PAGE_FOOTER_SLOT,
				DesignSchemaConstants.PAGE_FOOTER_TAG );
		writer.endElement( );
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.design.elements.DesignVisitor#visitParameterGroup(org.eclipse.birt.report.model.design.elements.ParameterGroup)
	 */
	public void visitParameterGroup( ParameterGroup obj )
	{
		writer.startElement( DesignSchemaConstants.PARAMETER_GROUP_TAG );
		super.visitParameterGroup( obj );
		property( obj, IParameterGroupModel.START_EXPANDED_PROP );
		resourceKey( obj, IParameterGroupModel.HELP_TEXT_KEY_PROP,
				IParameterGroupModel.HELP_TEXT_PROP );
		writeContents( obj, IParameterGroupModel.PARAMETERS_SLOT,
				DesignSchemaConstants.PARAMETERS_TAG );
		writer.endElement( );
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.elements.ElementVisitor#visitCascadingParameterGroup(org.eclipse.birt.report.model.elements.CascadingParameterGroup)
	 */
	public void visitCascadingParameterGroup( CascadingParameterGroup obj )
	{
		writer
				.startElement( DesignSchemaConstants.CASCADING_PARAMETER_GROUP_TAG );
		super.visitParameterGroup( obj );