LQ calibration updates (#577)

* Updates to LQ calibration

Added a few updates to the LQ calibration:
- Widened the energy range for finding DEP events
- Switched the time_correction from doing fits of the LQ distribution to just calculating the arithmetic mean and sigma
- Added a low-value cutoff for drift time values when performing the drift time correction fit.
- Final LQ values are now normalized by the fitted sigma from the cut fit. The cut value is now set to 3.

* Updated unit test with new argument

Added the argument for the drift time parameter

* Fixed time correction bug