function _fnGetCellData( settings, rowIdx, colIdx, type )
	{
		var draw           = settings.iDraw;
		var col            = settings.aoColumns[colIdx];
		var rowData        = settings.aoData[rowIdx]._aData;
		var defaultContent = col.sDefaultContent;
		var cellData       = col.fnGetData( rowData, type, {
			settings: settings,
			row:      rowIdx,
			col:      colIdx
		} );
	
		if ( cellData === undefined ) {
			if ( settings.iDrawError != draw && defaultContent === null ) {
				_fnLog( settings, 0, "Requested unknown parameter "+
					(typeof col.mData=='function' ? '{function}' : "'"+col.mData+"'")+
					" for row "+rowIdx+", column "+colIdx, 4 );
				settings.iDrawError = draw;
			}
			return defaultContent;
		}
	
		// When the data source is null and a specific data type is requested (i.e.
		// not the original data), we can use default column data
		if ( (cellData === rowData || cellData === null) && defaultContent !== null && type !== undefined ) {
			cellData = defaultContent;
		}
		else if ( typeof cellData === 'function' ) {
			// If the data source is a function, then we run it and use the return,
			// executing in the scope of the data object (for instances)
			return cellData.call( rowData );
		}
	
		if ( cellData === null && type == 'display' ) {
			return '';
		}
		return cellData;
	}
Get the data for a given cell from the internal cache, taking into account data mapping
 @param {object} settings dataTables settings object
 @param {int} rowIdx aoData row id
 @param {int} colIdx Column index
 @param {string} type data get type ('display', 'type' 'filter' 'sort')
 @returns {*} Cell data
 @memberof DataTable#oApi