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
writeUserPropertyValues( obj );
		writeStructureList( obj, IDesignElementModel.PROPERTY_MASKS_PROP );
	}
	/**
	 * Marks line number of element
	 * 
	 * @param obj
	 */
	void markLineNumber( Object obj )
	{
		if ( markLineNumber )
		{
			Object key = obj;
			Module module = getModule( );
			if ( module != null )
				module.addLineNo( key, new Integer( writer.getLineCounter( ) ) );
		}
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.elements.ElementVisitor#visitSimpleDataSet(org.eclipse.birt.report.model.elements.SimpleDataSet)
	 */
	public void visitDataSet( DataSet obj )
	{
		super.visitDataSet( obj );
		writeStructureList( obj, IDataSetModel.RESULT_SET_HINTS_PROP );
		writeStructureList( obj, IDataSetModel.COMPUTED_COLUMNS_PROP );
		writeStructureList( obj, IDataSetModel.COLUMN_HINTS_PROP );
		writeStructureList( obj, IDataSetModel.FILTER_PROP );