gh#1457 set default duration on switch to non-AllDay

[lmamane]

fixes enhancement request (issue) #1457

[Gitsaibot]

Seems to work. When testing I noticed that it can happen that the appointment is created twice. But I don't think that these changes are responsible for that.

How to reproduce:

1. click on an all day event in month view -> day view opens
2. long click on the event until new event dialog appears
3. click on the screen to cancel
4. click on the all day event -> now the event is loaded without title and when you save you have created a second event instead of customizing the first one.

[jspricke]

@Gitsaibot not sure I got all your steps right but I was not able to reproduce your steps in Etar 1.0.34. Can you reproduce without this patch?

This sounds fine to me otherwise.

[Gitsaibot]

I only testeted with version 1.0.36 and there i can reproduce(with and without) it.