Gamma ray refactor

[andrewfullard]

📝 Description

Type: 🚀 feature

Refactoring of the gamma-ray code to allow for easier modification.

🚦 Testing

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☑️ Checklist

• I requested two reviewers for this pull request
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[codecov]

Codecov Report

Merging #2139 (09a4183) into master (e3184f4) will increase coverage by 0.14%.
The diff coverage is 29.32%.

@@            Coverage Diff             @@
##           master    #2139      +/-   ##
==========================================
+ Coverage   61.63%   61.77%   +0.14%     
==========================================
  Files          75       78       +3     
  Lines        8649     8859     +210     
==========================================
+ Hits         5331     5473     +142     
- Misses       3318     3386      +68     

Impacted Files	Coverage Δ
tardis/energy_input/gamma_ray_grid.py	19.60% <0.00%> (ø)
tardis/energy_input/GXPacket.py	33.33% <10.00%> (-25.93%)	⬇️
tardis/energy_input/samplers.py	34.09% <34.09%> (ø)
tardis/montecarlo/montecarlo_numba/opacities.py	38.18% <34.54%> (-3.64%)	⬇️
tardis/energy_input/gamma_ray_interactions.py	20.40% <50.00%> (ø)
tardis/energy_input/util.py	32.30% <100.00%> (ø)
tardis/montecarlo/packet_source.py	79.24% <0.00%> (-18.20%)	⬇️
tardis/plasma/standard_plasmas.py	70.09% <0.00%> (-4.40%)	⬇️
tardis/montecarlo/montecarlo_numba/vpacket.py	20.56% <0.00%> (-1.23%)	⬇️
tardis/montecarlo/base.py	86.97% <0.00%> (-0.64%)	⬇️
... and 15 more

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[andrewfullard]

Refactor and original code are matching, it was a case of differences in gamma-ray data processing from sandia vs NNDC. Need to closely investigate the gamma-ray spectra differences and consider which data to use.

NNDC data from nuclear:

Sandia data seems to lead to more energy deposition at late times:

The sandia decay data stores the end-point energies for positrons, which is not actually what we want (or at least, it's not what anybody else uses).

[Rodot-]

A few bits of code are not covered by tests, but that seems fine for now as they would require integration tests