Handle the iso8859-1 charset somewhat, so that when the po file is in

Handle the iso8859-1 charset somewhat, so that when the po file is in
either iso8859-1 or utf8, msgmerge(1) won't crap out. The code is ugly;
the conversion table is hard-coded, and in some place not very appropriate.

However, this does fix the case where a few strings containing French
characters can't be translated. As a side effect, tmpl_process3 can now
also be used for French or other languages using iso8859-1.