Format datetimes in cells as FORMAT_DATE_DATETIME
Created originally on Bitbucket by bgelineau (Brice Gelineau)
Was already merged in Bitbucket before import, marked as merged by the import user
When setting the value of a cell to a datetime, use FORMAT_DATE_DATETIME
instead of FORMAT_DATE_YYYYMMDD2
as the default format.
Maybe we should also change FORMAT_DATE_DATETIME
or create a new format for consistency with YYYYMMDD2
?