Reading "random groups"

[aplavin]

FITSIO.jl is missing random group HDU reading, a format widely used in some fields such as radiointerferometry. Until recently, I was using astropy through PyCall for that.
A few days ago, I implemented basic groups reading in https://github.com/JuliaAPlavin/VLBIData.jl/blob/master/src/grouphdu.jl. I tested that it gives the exact same results as astropy on thousands of (similar) fits files, so it works.
Some cleaning and deciding on the output format would be needed in order to include it into FITSIO.jl itself. If someone gets to this before myself, please do!