100 bugs, fix one, 110 bugs in the code

Author: Christian Muehle

lib/datatable.dart

@@ -531,8 +531,6 @@ class PaginatedDataTableState extends State<AdvancedPaginatedDataTable> {
                   if (newRowsPerPage != null &&
                       newRowsPerPage != widget.rowsPerPage) {
                     print('change rows per page to $newRowsPerPage');
-                    _firstRowIndex =
-                        _firstRowIndex + widget.rowsPerPage - newRowsPerPage;
                     setLoadNextPage(rowsPerPage: newRowsPerPage);
                     if (widget.onRowsPerPageChanged != null) {
                       widget.onRowsPerPageChanged!(newRowsPerPage);