function _fnAddColumn( oSettings, nTh )
	{
		// Add column to aoColumns array
		var oDefaults = DataTable.defaults.column;
		var iCol = oSettings.aoColumns.length;
		var oCol = $.extend( {}, DataTable.models.oColumn, oDefaults, {
			"nTh": nTh ? nTh : document.createElement('th'),
			"sTitle":    oDefaults.sTitle    ? oDefaults.sTitle    : nTh ? nTh.innerHTML : '',
			"aDataSort": oDefaults.aDataSort ? oDefaults.aDataSort : [iCol],
			"mData": oDefaults.mData ? oDefaults.mData : iCol,
			idx: iCol
		} );
		oSettings.aoColumns.push( oCol );
	
		// Add search object for column specific search. Note that the `searchCols[ iCol ]`
		// passed into extend can be undefined. This allows the user to give a default
		// with only some of the parameters defined, and also not give a default
		var searchCols = oSettings.aoPreSearchCols;
		searchCols[ iCol ] = $.extend( {}, DataTable.models.oSearch, searchCols[ iCol ] );
	
		// Use the default column options function to initialise classes etc
		_fnColumnOptions( oSettings, iCol, $(nTh).data() );
	}
Add a column to the list used for the table with default values
 @param {object} oSettings dataTables settings object
 @param {node} nTh The th element for this column
 @memberof DataTable#oApi