%%pretty should be turned on for the whole notebook

[winston-zillow]

Is your feature request related to a problem? Please describe.
Currently, one has to annotate any and all cells doing df.show() or similar with %%pretty to have the resulting table prettified.

Describe the solution you'd like

1. By default turn on prettify for the whole notebook
2. Add option to %%pretty to turn off the default
3. Add options to %%pretty to toggle the prettification on a cell.

[winston-zillow]

@devstein any thought on this suggestion? Basically the default should be to prettify the outputs

[devstein]

@winston-zillow %%pretty is a cell magic (the %% prefix), so it should't operate on multiple cells.

I'm open to creating an equivalent notebook magic %pretty that operates over the entire notebook and a flag%%pretty --disable for disabling it on a specific cell.

Is this something you are open to contributing?