Flow Schedule conflicts

[elias-pap]

Zones that are scheduled for the same day at the same hour should appear highlighted in red, to indicate conflict.

[ggalan87]

That's ok if someone "accidentally" edited the XML by hand, but otherwise I think such situation should be prevented by checking user's input.

But there is also a use case when someone's intention is to temprorarilly be in a faulty state. That happens when someone wants to shrink a Zone in order to schedule another Zone in between. Thus it's ok to just have an indicator for the overlap.