Second cut at syncing our desktop background with GNOME's (bug 1047)
	Now we support images being centered and scaled (not just tiled)
	Although, there is no UI in nautilus to set this up (use the background
	capplet) Still need to handle update issues.

	* libnautilus-extensions/nautilus-background.c:
	(nautilus_background_destroy),
	(nautilus_background_get_image_placement),
	(nautilus_background_set_image_placement),
	(nautilus_background_draw), (nautilus_background_draw_aa),
	(nautilus_background_get_image_uri), (load_image_callback),
	(start_loading_image),
	(nautilus_background_receive_dropped_background_image),
	(nautilus_background_set_image_uri), (nautilus_background_is_set),
	(nautilus_background_real_reset),
	(nautilus_background_is_too_complex_for_gtk_style),
	(nautilus_background_is_dark),
	(nautilus_background_receive_dropped_color):
	* libnautilus-extensions/nautilus-background.h:
	* libnautilus-extensions/nautilus-directory-background.c:
	(nautilus_directory_background_get_default_settings),
	(nautilus_directory_background_read_desktop_settings),
	(nautilus_directory_background_write_desktop_settings),
	(nautilus_directory_background_write_desktop_default_settings),
	(nautilus_directory_background_is_set),
	(background_changed_callback), (directory_changed_callback),
	(background_reset_callback):

	nautilus_gdk_pixbuf_scale_to_fit was renamed to
	nautilus_gdk_pixbuf_scale_down_to_fit and also changed
	to not unref it's argument pixbuf. This involved fixing
	up various places it was used.

	* components/music/nautilus-music-view.c:
	(nautilus_music_view_update_from_uri):
	* libnautilus-extensions/nautilus-gdk-pixbuf-extensions.c:
	(nautilus_gdk_pixbuf_scale_to_fit_helper),
	(nautilus_gdk_pixbuf_scale_to_fit),
	(nautilus_gdk_pixbuf_scale_down_to_fit):
	* libnautilus-extensions/nautilus-gdk-pixbuf-extensions.h:
	* libnautilus-extensions/nautilus-icon-factory.c:
	(nautilus_icon_factory_make_thumbnails):
	* src/nautilus-property-browser.c: (make_drag_image),
	(set_emblem_image_from_file),
	(make_properties_from_directory_path):
	* src/nautilus-sidebar.c: (background_settings_changed_callback),
	(background_reset_callback), (nautilus_sidebar_update_appearance):
	* src/nautilus-theme-selector.c: (add_theme):