Japanese and spanish start page

[Bill Allombert <allomber@math.u-bordeaux.fr>]

Dear PARI-dev,

I have added Japanese and Spanish translation of the
intro page of http://pari.math.u-bordeaux.fr.

Those translation have not been reviewed as much as the
others, and I tweaked them to fit in the html page, so
if you are a Japanese or Spanish speaker, please check
them for correctness.

If your browser is configured to select your native
tongue automatically (see e.g. http://www.debian.org/intro/cn
for how to do that), you should get the translated page
automatically, else you can go to
http://pari.math.u-bordeaux.fr/index.XX.html
, where XX is the code of your tongue (es for spanish, 
ja for japanese).

Cheers,
Bill.