more "Overview" feedback

[antifuchs]

I just got the "overview" function to work on my 1.1alpha7 test installation. Some things that I'd like to see changed:

• Don't display data or triggers for items that no host in the group supports. Host.SNMP template hosts with only few interfaces are very verbose in this view.
• In the "Data" and "Trigger" overview, link the triggers/items/data to their historical graph.

Thanks,
Andreas.