Add modify_header(unhide_hidden) argument?

[ddsjoberg]

I was working with a table where I needed to assign the names and I used ends_with("_1"), and it ended up unhiding a bunch of columns i didn't want to be shown.

Another option would be to include a new selectors all_hidden_columns()and all_unhidden_columns().

Maybe all of the above, but I think scoping the hidden data for selecting may be overkill?