First draft of qfauto/qfisom

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

Dear PARI developers,

I have been working on a port of Bernd Souvignier ISOM program for
computing automorphisms and isomorphisms of lattices.

As a result, I have created a git branch bill-qfisom-stage1
which adds two functions qfauto and qfisom.

<http://pari.math.u-bordeaux1.fr/cgi-bin/gitweb.cgi?p=pari.git;a=shortlog;h=refs/heads/bill-qfisom-stage1>

This implements all AUTO/ISOM options except for the use of scalar product
combinations which is not finished yet.

When the same options are set, it is much faster than Souvignier program, but I
do not know exactly why.

The user interface is quite limited. In particular it assumes the "best"
matrices are given for the lattices, and there is no way to tune the
algorithm.

Also there is no way to precompute invariant of one form for faster 
computation of isomorphisms with others.

Please test and give feedback about how you like it to work.

Cheers,
Bill