Drastically increase performance on deleting large amounts of rows.
Currently, min and max column are calculated once for each row to be deleted. And this calculation needs to iterate over every cell.
Deleting lots of rows (say 19k of 75k rows in total) thus can take hours (sic!). After this patch, a couple seconds are sufficient.
Thanks for this. Never worked on such large sheets myself. Probably needs doing for rows as well.
I suggest you use min_col and max_col as variable names.