Showing a file in the file manager

[Federico Mena Quintero]

Hi, everyone,

We are starting to add a command "Show in file manager" to apps that let
you open files (text editor, image viewer, word processor, etc.).  This
is similar to the command that Firefox has in the right-click menu in
its Downloads list.

In Gnome you can do

	nautilus file:///foo/bar.txt

and it will open a window to show the "foo" directory, with the
"bar.txt" file selected.