`math` refactor and `pargen` updates

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 44.01232% with 1454 lines in your changes are missing coverage. Please review.

Project coverage is 50.05%. Comparing base (e7b7b36) to head (7950c34).

Files	Patch %	Lines
src/pygama/pargen/data_cleaning.py	26.07%	360 Missing :warning:
src/pygama/pargen/dsp_optimize.py	0.00%	299 Missing :warning:
src/pygama/pargen/energy_optimisation.py	4.19%	160 Missing :warning:
src/pygama/pargen/extract_tau.py	0.00%	102 Missing :warning:
src/pygama/pargen/dplms_ge_dict.py	0.00%	56 Missing :warning:
src/pygama/math/histogram.py	65.16%	54 Missing :warning:
src/pygama/math/hpge_peak_fitting.py	65.32%	43 Missing :warning:
src/pygama/math/functions/exgauss.py	54.65%	39 Missing :warning:
src/pygama/math/functions/sum_dists.py	83.81%	39 Missing :warning:
src/pygama/pargen/lq_cal.py	25.00%	39 Missing :warning:
... and 19 more

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #545 +/- ## =========================================== + Coverage 21.34% 50.05% +28.71% =========================================== Files 42 63 +21 Lines 7907 7581 -326 =========================================== + Hits 1688 3795 +2107 + Misses 6219 3786 -2433 ```

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[jasondet]

Sam fixed the errors -- I'm going to merge!