[tex-eplain] \sidx not catcode-clean

[Karl Berry]

      2) leave \?idx* macros alone by default but give the user
         an option to convert them into `verbatim argument'
         macros.

Doesn't this also have the hyperlink problem?  Not that I see a way to
solve it.

Anyway, beyond Eplain's parsing of the index terms, there is also
makeindex to be concerned about, which has a ton of special characters
itself.  I don't think it's feasible to really be able to handle index
entries with anything.  That would mean Eplain has to somehow escape the
makeindex special characters (which can themselves be redefined) and
then unescape them, in the midst of this purportedly verbatim string.
Yikes ... or am I totally misunderstanding?

I guess it is good to have a switch to make the index parsing be
verbatim/non-verbatim, rather than defining more commands.

Thanks,
karl