support for 1D models + thermal conduction in hydro

[n-claes]

PR description

Adds a hd-1d physics type, support for isotropic thermal conduction in HD and a custom heating term.

New features

Legolas

• a new hd-1d physics type for 1D hydro models along a fixed field line
• new option in the parfile to enable custom heating
• option to disable forced thermal balance, allowing for runs in non-thermal equilibrium
• option to set units based on numberdensity, length and temperature

Bugfixes

Legolas

• fixed crash when thermal conduction was enabled in hydro (due to division by B0^2)

Pylbo

• fixed issue when interactively plotting derived eigenfunctions if there is only 1 element in the state vector (i.e. only S when in 1D)

TODO

• add unit numberdensity support to the parfile

[codecov]

Codecov Report

Merging #125 (a35eb30) into develop (ff5a017) will decrease coverage by 0.28%.
The diff coverage is 84.61%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #125      +/-   ##
===========================================
- Coverage    91.73%   91.45%   -0.28%     
===========================================
  Files          148      148              
  Lines         8223     8328     +105     
===========================================
+ Hits          7543     7616      +73     
- Misses         680      712      +32     

Flag	Coverage Δ
legolas	93.15% <85.58%> (-0.43%)	⬇️
pylbo	88.49% <50.00%> (-0.08%)	⬇️

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