To make font embedding work in an epub in ibooks, this file needs to be in the epub:
with this content:
<?xml version="1.0" encoding="UTF-8"?>
Do I just not see how to do that in calibre? At the moment, the only way I can get that into it is to cleverly drag it in via winzip. Seems a plugin might be a good idea, but my python skills are worse than everyone else's.
Or maybe it's already done and I just don't know where to look?