Have metadata printing be IO aware, metadata printing improvements in general #416
Description
Currently when running Dataframes in a Jupyter notebook, the data frame prints out in html form properly, but when you do printlabels(df) you get a boring text representation.
Plus in general, it would be really nice to have a way to deal with very large data frames and print labels for all columns, maybe to make it compatible with DataFrame that can be viewed with @less from TerminalPager.jl.