* door-gnus.el: c-u q to gnus-group-exit

Signed-off-by: Yakkala Yagnesh Raghava <hi@yagnesh.org>
* door-gnus.el: add num arg to quit gnus

Signed-off-by: Yakkala Yagnesh Raghava <hi@yagnesh.org>
* door-gnus.el: place autoload cookie

Signed-off-by: Yakkala Yagnesh Raghava <hi@yagnesh.org>