places: search for bookmarks in ~/.config/gtk-3.0/bookmarks.

As in Semplice 7 we are using a PCManFM version compiled against GTK+3.0,
we need to check for bookmarks there.
places: changed icon names for remote folders
mpris: use the extensionName as the actual extension when generating ExecuteActions.

The sys.argv[1] method is not reliable as as the first command line argument is not
necessairly the extension.
mpris: use music-player icon as the song title's icon.
xdgmenu: comment out oneslip checks as the web applications feature has been removed from bricks.
xdgmenu: ensure we get the entire command to execute and not only the executable.
logout_vera: modified some icons.
1.30.1