Custom Field Previews#42

The existing content list views (both the full-page views, and the embedded views for relations in the record editor) are a little hard to read. I’d like the ability to control how those display. For example, if I have Article and Author models, I’d like to edit the relation in the Article to display each author’s first and last name.

A simple version of this could just have a flag for fields to display, or you could go fancier and use templates, e.g., <%= author.firstName %> <%= author.lastName %>

This seems to be related to #29. Will add your comment there as well and archive this, so we do not get duplicates!