bug#13041: 24.2; diacritic-fold-search

[Drew Adams]

> > Typing "suf" as search string would go to "suffer".  Adding 
> > an "f" to the search string now would go back to "su?er" (or not).
>
> Going back looks like backtracking in the regexp search.
> 
> OTOH, instead of using an approach of matching only a full match
> like in Chromium, we could do like GEdit and OpenOffice that
> match the whole ligature character in a partial match
> (i.e. to match "?" when the search string is just "f").

Seems to me that the starting point should be the Unicode Regexp spec, which
outlines the behavior of level 1 and level 2 searches.  Emacs Dev can choose
what it wants to do, of course, but that is a good place to start, I think.