reorder_baselines loses data

[pboley]

The reorder_baselines method of the Obsdata class assumes that any observations obtained on telescopes (t1, t2) and (t2, t1) are conjugates of each other, and throws away one of the two. However, this is not generally they case, in particular if the observations were obtained at different times and/or frequencies.

I discovered this when importing an OIFITS file, only to find that of the 60 or so wavelengths in the file, only a single one remains after reorder_baselines is run.