Add setting to ensure that linked assets are present in parent folder #170
Description
At the NYT, we've run into some persistent workflow issues in handing off work between editors, where we'll be missing the source images, reference maps, etc., that are used in the original illustrator file to generate the ai2html graphic.
This is an issue when we're doing preparation for print (which in our case, usually takes place after the web graphic has published).
Ideally, there'd be a setting that could trigger an error when a placed or linked file is not included within the parent directory of the illustrator file? That way, we could verify that we're including all the source dependencies when producing an ai2html.
cc @wmandrews