PretiMODIT: inverse T-grid instead of Elower

[HajimeKawahara]

I feel that the inverse T grid should be tried as one of the LBD grids instead of Elower.

tag: Precomputation+T inverse+MODIT

maybe good

• less sparse than E-grid (at lower E)
• can integrate q(T) and f(T,E)
• similar error, according to analytic estimates, not super confident

[HajimeKawahara]

See also #311 and #318

[HajimeKawahara]

[HajimeKawahara]

Roadmap

• [x] max Elower for given Tmax and Pmin (opagird.py)
• [x] analytic derivation of the residual
• [x] 1st derivative correction
• [x] 2nd derivative correction
• [x] residual check in reality
• [x] Opacity Calculator class (opacalc.py)
• [x] broadening parameter grid optimization
• [x] Forward modeling check
• [x] Reverse modeling check

[HajimeKawahara]

implemented in #332