Experimental javascript port of GP

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

Dear PARI developers,
Following Bernard Parisse (the author of xcas) demo
at the Ateliers, I have built PARI/GP to javascript using emscripten.

The result is a version of GP that run in your browser.
You can try it at
<http://pari.math.u-bordeaux.fr/gp.html>

It has close to the same feature set as the stand-alone windows binary.
The speed depends on your web browser. 
With firefox, it is about four time slower than a native binary.
(part of the slowness being due to javascript missing support for
64bit integers, so PARI is compiled for 32bit).

One test is 
factor(2^128+1)

you can time it using 
my(t=getwalltime());factor(2^128+1);getwalltime()-t

(gettime() does not work)

Cheers,
Bill.