API option `ignore` should accept an array

[thw0rted]

There are two prettify options that take a list of strings, errorLikeObjectKeys and ignore. The former accepts an array of strings, while the latter wants a comma-separated list.

I actually came here to suggest that ignore should run trim on all values -- ignore: "pid, hostname" is treated as ignore: "pid" because the space in the value causes hostname not to match. But after looking at the docs, and seeing how errorLikeObjectKeys is handled, it would be more consistent to accept an array (while retaining backward compatibility with the CSV version).