Support SNEWPY’s pre-SN models

[JostMigenda]

SNEWPY v1.5 added support for pre-SN models. In principle, it shouldn’t be too hard to support them in sntools; however, there are probably a couple of implicit assumptions in the code (like 1ms time binning) that won’t work for pre-SN models.

[JostMigenda]

As always, the devil is in the details. 😅 @eobrien2502 is working on this and has discovered a couple of bugs/inconsistencies in snewpy as well as sntools; but they’re making good progress.

Open issues:

• Consistent treatment of self.metadata between ccsn and presn models snewpy#394
• Odrzywolek_2010: get_initial_spectra does not accept scalar energies snewpy#395
• Should we ensure model.time is sorted from earliest to latest time? snewpy#399 (can handle this in sntools, without changes to snewpy)
• the preSN models use a lambda function for interpolation, which is unpickleable and thus isn’t handled well by the ProcessPoolExecutor in sntools