different encodings for input and output file names and command line

[Patrice Dumas]

Hello,

First, some tests with locales different from the @documentencoding made
me realize that it would make sense to have a different encoding of
file names for output than for input.  Indeed, it may make sense for the
input files names (@include, @verbatiminclude) to match the document encoding
when extracted from an archive, for example.  But even in that case
encoding the output names using the @documentencoding is very dubious,
especially since we often use a different output encoding for the file
content than the @documentencoding.

Another use case stirs even more in this direction.  In the init files
(latex2html, tex4ht, highlight syntax), there are some commands launched
from texi2any.  It seems to me natural and less error prone to encode
those command lines in the locales encoding.  But this also forces the
file names referenced in those command lines to be in the locales
encoding.

In any case, handling all the different situations makes it necessary
to be able to disconnect the input file names encoding from the output
file names encodings, consistently with what we do with documents
encodings.  I will do the corresponding code anyway and allow both the
locale to be used and the @documentencoding in both cases based on
customization variables switches.  The question that remains is what to
use for the defaults and for the command lines.

My proposal is:

* input file name encoding:
   My preference would be the locale, but Gavin proposal to use
   @documentencoding also has merit, so let stick to @documentencoding
   except on Windows where the locale is used.
* output file encoding:
   Use the locale in the default case.
* command lines called from texi2any
   Always use the encoding already used for messages defaulting to the
   locale encoding

Opinions, ideas?

-- 
Pat