Structured array properties of DataModels should not be converted to FITS_rec

[mcara]

PR #1754 introduced automatic conversion of structured array properties to FITS_rec. In my opinion, DataModel attributes should have the type described in corresponding schemas which is unexpected. Therefore, I think #1754 should be rolled back and handling of units in FITS tables should be handled separately.

CC: @hbushouse @perrygreenfield @nden

[hbushouse]

I agree that having things converted to FITS_rec within a datamodel is a contrived solution to problem of attaching units (and any other column attributes). If someone can find a way to handle these types of column attributes that doesn't require conversion to FITS_rec (at least not within the datamodel itself - conversion should happen only when serializing to a FITS file), I'm all for reverting #1754. But we do need the column units - so that problem needs to be figured out first.

[mcara]

I agree with you that units must work. I believe this is possible, but it will not be trivial and quite time consuming to do it carefully.

[jdavies-st]

Labelling this as a bug, as the result of this behavior means that any units (i.e. TUNIT) described in a FITS binary table get dropped on the floor when read in as a datamodel.