Display nice and iowait in CPUGraph

Submitted by JD

Assigned to Xfce-Goodies Maintainers

Link to original bug (#7579)

Description

I've noticed that nice and iowait are 2 CPU usage states that are not displayed in the cpugraph plugin. I think they're rather useful to add because (as an example) last night, my bittorrent client was i/o waiting my system to hell and I wouldn't really have known what was going on unless I had the GNOME cpu monitor applet in my panel (my desktop is still on GNOME ATM) and i was able to see the problem, kill the process and all was happy.

I think this is a quite useful feature and it may be doable by just moving iowait to used instead of total (Or give it its own variable since it's not REALLY CPU usage, but it sort of is).