Created originally on Bitbucket by René Neumann
Was already merged in Bitbucket before import, marked as merged by the import user
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.
(This is a redo of pull request #341 (closed), because I couldn’t update that one to use the correct branch)