datetime.(from_excel, to_excel): drop excel bug workaround
The specification is clear on how to (de)serialize dates in the 1900 date system. Instead of attempting to follow what Excel does (which we can't do fully anyway), let's follow the specification. This increases interoperability and allows correct timedelta calculations for time differences above 60 days.
topic/default/timedelta in 5 minutes and 38 seconds (queued for 1 second)7 jobs for