New GP evaluator release 2.4.1.compile-5

[Bill Allombert <Bill.Allombert@math.u-bordeaux1.fr>]

Hello PARI-dev,

I have made available a new version of my latest GP evaluator:

<http://pari.math.u-bordeaux.fr/~bill/pari-2.4.1.compile-5.tar.gz>

This version allow functions, formal variables and local variables
to share the same name.

The compiler has been changed never to copy the program text. This 
is faster and reduce memory usage.

Now I consider the new GP evaluator to be mostly completed.

The part that I might want to change is the bytecode format.
I lack experience about the various trade-off involved and whether
it is worth the trouble to store opcodes on a single byte instead 
of four.

Cheers,
Bill.