#88 reference field overhaul

[Roger Burks]

I was thinking about the references tab, and it occurred to me that there's no field for a book's editor when you're entering a chapter citation, which would be standard for most citation styles. Maybe the book should be selectable from an autocomplete field, and this would partially make the issue a bit easier, especially to make it standard. But trying to avoid digression here: I think we at least need a book editor field.

[Matt]

IIRC you can get this functionality by setting the "is" column to "editor" and then selecting "book section" as reference type. Let me know if this works, if not I'll tweak.