mkrelease.sh: implemented 'shellvar' command to extract configure.in versions
mkrelease.sh: implemented 'shellvar' command to extract configure.in versions

tim-janik/beast,swesterfeld/beast,GNOME/beast,GNOME/beast,GNOME/beast,tim-janik/beast,tim-janik/beast,swesterfeld/beast,GNOME/beast,swesterfeld/beast,GNOME/beast,swesterfeld/beast,GNOME/beast,tim-janik/beast,tim-janik/beast,tim-janik/beast,swesterfeld/beast,GNOME/beast,tim-janik/beast,swesterfeld/beast,swesterfeld/beast