texinfo translations reenabled



Hello,

Following earlier discussion I've reenabled the Makefiles for
doc/info/es and doc/info/pt .
I've committed texi2html 1.76 to Maxima cvs as we discussed.
doc/info/Makefile.am and doc/info/{es,pt}/Makefile.am all use
the private texi2html 1.76 now.

doc/info/{es,pt}/Makefile.am has infodir = @prefix@/info/{es,pt}
so maxima.info* files in {es,pt} are copied to a subdirectory of
@prefix@/info .

With these changes, make and make install succeed,
and the generated html and info files are good.
In particular accents and other diacriticals are processed correctly.

Hope this helps,
Robert Dodier