Zero out rmin -> rmax regions

[marshallmcdonnell]

Per the original StoG, you could:

• enter rmax to "delete" / flat-line a region from 0 -> rmax
• you also entered a peak_min and peak_max to "save" the peak region so it did not get flat-lined

Would like to add this same functionality along with a different input mechanism:

• Enter a list of [(rmin, rmax)] pairs where you flat-line the regions between these.

Then, to replicate the old behavior, you would enter the following list:

[(0, `peak_min`), (`peak_max`, `rmax`)]