Pixel-like Threshold Scan for strip modules

The traditional approach for Threshold scans in the Strip community is to fix the injected charge to a module and vary the channel threshold, while the Pixel community follows the opposite approach, fixing the thresholds for each of the channela and then perform the scan varying the injected charge.

This pixel-like approach enables to fit a non-reverse S-curve (differently from the strip-like approach) and, by fixing the thresholds in advance, allows to be less susceptible to noise, avoiding potential double-knees/shoulders in the S-curves.

Documentation on this can be found in !517 (merged) and at the link here