Give bar graphs sensible ranges, fix auto-calibrate
The min-range was 0-10000 while max would only go 0-100. This suggests some leftovers from the bar graphs being mostly, or almost-only, for percentages. The auto-calibration was also a bit wonky.
- give all the spinners the same range (0-10000)
- when setting range to 0-0 (the tooltip says this will auto-calibrate), also do that after the dialog closes, not just on next start of ksysguard
- while here, remove an unused variable (left over from some previous auto-calibration experiment)