Added set_index_column($name) function, which sets the "DT_RowId" field to output array, for DataTables to use as row reference IDs
Added new function to README
Merge pull request #97 from langabi/master

Added function set_index_column to set the DataTables row index (DT_Row_ID / http://datatables.net/reference/api/row%28%29.index%28%29)