Node doesn't keep stderr size updated

[evs-chris]

...but it does keep stdout updated, so this switches to using process.stdout.columns. I suppose the only risk would be that someone redirects stdout but not stderr?

[Rich-Harris]

Huh, weird, what does that mean in practice? Seems like using the more accurate measure is appropriate thing to do either way, will merge - thanks

[evs-chris]

Very weird... there was some face-palmage when I realized why resizing my gobble tmux pane was doing slightly strange things to the output. In practice, if you run gobble 1>/dev/null, you get an exception because you can't read a width off a non-tty descriptor. I can't fathom why you'd ever try to run like that, but I can prevent it. I'll send another PR in a minute.