use ENABLE_ENCODING for Info only

[Patrice Dumas]

Hello,

If I recall well, there was some previous discussions, I believe Gavin
proposed something similar.

As it is now --enable-encoding (ENABLE_ENCODING customization option)
means something very different for Info/Plaintext and HTML/XML based
formats.  For Info/Plaintext is means using actual characters and not
ASCII transliterations as far as poosible.  For HTML/XML
--enable-encoding means using characters instead of entities.  It means
something very different, in HTML/XML encodings support is enabled in
any case (though not necessarily fully when encoding is US-ASCII), but
the option is really about entities or not.

I would propose that ENABLE_ENCODING only says something on supporting
encodings or not, and that it has not much effect except for Info and
Plaintext.  I propose to use a customization variable for HTML/XML,
for example named OUTPUT_CHARACTERS.

What do you think?

-- 
Pat