Since we also support passing a basename now, clients might be interested in knowing the path used to save the file. Add an out argument to the interface for that. https://bugzilla.gnome.org/show_bug.cgi?id=688004
And fix its declaration.
Split the screenshot functionality from ShellGlobal into its own class. https://bugzilla.gnome.org/show_bug.cgi?id=670086