Merge: GNU readline wrapper

This is a tiny wrapper for the GNU readline library. For some reasons, pkg-config doesn't know about libreadline so I had to hardcode the cflags using the ldflags module annotation.

Signed-off-by: Frédéric Vachon <fredvac@gmail.com>

Pull-Request: #2083
Reviewed-by: Jean Privat <jean@pryen.org>
Reviewed-by: Etienne M. Gagnon <egagnon@j-meg.com>
Reviewed-by: Alexis Laferrière <alexis.laf@xymus.net>