Ahaggar: Update README file with Copyright

Signed-off-by: Djalal Harouni <tixxdz@opendz.org>
Ahaggar: Add the buffer.h header file

This file includes different declarations of buffer handling routines

Signed-off-by: Djalal Harouni <tixxdz@opendz.org>
Ahaggar: Add the buffer.c file

Definitions of the buffer routines which are used to simplify
output handling.

Signed-off-by: Djalal Harouni <tixxdz@opendz.org>