General:
  ☐ Auto 3D-to-2D conversion for range-independent environments
  ☐ Validate noise model (shows variability in PSD with sampling rate)
  ☐ Scatterers
  ☐ Add arbitrary signal source

Bellhop:
  ✔ Add support for Gaussian beams @done(20-11-23 13:29)

RaySolver:
  ☐ Find a way to allow full derivative through a dependent θ
  ☐ Limit beamwidth to deal with caustics?
  ☐ Fix numerical stability problems seen in long range low frequency scenario
  ☐ :smooth interpolation for SSP does bad things to q (caustics?)

Docs:
  ☐ Propagation modeling guide
  ☐ Developing propagation models
  ☐ Differentiability & Turing with propagation models

Tests:
  ☐ Comparison tests between models
  ☐ Performance tests
  ☐ Turing tests

KIV:
  ☐ 3D Bellhop
  ☐ 3D RaySolver
  ☐ 2D/3D SSP
  ☐ 2D bathymetry
  ☐ Source directionality
