I know there's *some* way to do this, because this is exactly what
Google Translate does. If you translate a page, it appears as English,
but when you highlight it and copy it elsewhere, you get alternate
French & English sentences.
-------
But anyway, I've written a crude Unicodifying plugin. It turns out
that even just going character by character, you get pretty
serviceable Unicodifying; there are lots of errors that Yi's apparent
lexing avoids*, but it's a start.
* still haven't figured out how Yi does it. Yi.Char.Unicode isn't
imported anywhere!
--
gwern