date/time format

[Bertin]

Not much of an issue, but a suggestion instead.
On line 51 of export.py, the code would be break if HTML calendar is already in 24hr mode.
This code could fix it >> #in_time = datetime.strptime(time, "%H:%M%S")

Ref: https://docs.python.org/3/library/datetime.html?highlight=datetime%20strptime#strftime-strptime-behavior

[Matteo Gisondi]

Unfortunately this format changes all the time. So sometimes it works and others it doesn't.

No use in future proofing something that breaks intermittently anyway.