[Nautilus-list] PATCH: add 'edit launcher' button to properties window

[Frank Worsley <fworsley shaw ca>]

Hi, 

attached is a patch that adds an "Edit Launcher" button to the properies
window when viewing properties for a file of type
'application/x-gnome-app-info'.

It makes it a lot easier to edit the desktop items or making changes to
the "applications:///" uri items.

One problem right now is that Nautilus doesn't always refresh the file's
icon/name after the file has been edited with gnome-desktop-item-edit
(which is launched by the button). Not sure how to fix that.

The other patch is for eel and adds two convenience functions that I
used in the nautilus patch.

If ok, please commit.

- Frank