git-attic: add script to list deleted files

Courtesy http://chneukirchen.org/blog/archive/2013/01/a-grab-bag-of-git-tricks.html.

Signed-off-by: Christopher Larson <kergoth@gmail.com>
vipe: add script to pipe in and out of $EDITOR

Signed-off-by: Christopher Larson <kergoth@gmail.com>