Allow Quantity to be written as a normal column to VOTable solves #3685 #6132
Work in Progress:
The travis failure seems unrelated.
@AustereCuriosity - this looks all OK to me now.
The failure is unrelated, but I'd like to have this properly tested just in case. So, it will need a rebase after #6142 is merged (or an alternative to it). Unfortunately, travis seems pretty stuck... (I canceled your travis runs just to try to get it sped up a bit).