⟨3D⟩ Stagger-Grid models

[andycasey]

Points:

• [x] Create a parser to read them from TSV and pickle.
• [x] Do they have any preference for which photospheric quantities are supplied to MOOG? (e.g., which depth scale?)
• [x] Upload pickled photospheres to Zenodo and update setup.py
• [x] Check units of quantities going into MOOG