Python representations/interfacing of Spectra and related data interchange

Prompted by this topic, I'm making this topic as a way to have a slightly more fine-grained discussion/voting area. So this topic is about interfacing spectra.

This is probably going to be the domain of specutils. That's currently quite limited in its capabilities, but that's the "vision". My opinion is that specutils should contain that sort of thing *and* some useful standard analysis tools/transformations (e.g., smoothing, spectral coaddition), but that's open for debate/work.