[horde] [whups]: updated whups-mail-filter.h: prevent duplicate events

[Carsten]

Hi all,

I have continued to play with the whups-mail-filter.
The next step was to sort out duplicate events.
Examble: every 5 minutes the drive space warning message is generated 
and send to the automation bus.
In raw version this would generate a ticket every 5 minutes.
In this version, the subject is read and if matches with an unresolved 
ticket, it will update the existing ticket only.

Now You can generate IDs on the monitoring agent for an ongoing event 
and put it into the ticket. Even so, if the same message occours after 
it was solved and the ticket is not jet set to resolve this fast, it 
would then generate a new one to tell the agent: I have seen Your 
action, but the issue is back.

Many ways to play.

Have fun

Carsten

https://drive.google.com/open?id=1ldH2VFNxplSvjoIeMl_FhrmdT0oUPLhS