missing grid points from util_ManualOverlapGrid

Running

```
util_ManualOverlapGrid.py --inj mdc.xml.gz --event 0 --parameter 'mtot' --parameter-range '[110,160]' --parameter q --parameter-range '[0.1,1]' --skip-overlap --verbose --grid-cartesian-npts 6
```

should produce 9 points, but only 8 points are generated. If you change the upper q range to [0.1,0.999999], you indeed get 9 output points.  