added preferences for the maximum numder of items per site and
	the update interval.  It's not quite finished, as the news
	view isn't watching the update interval preference yet.

	* components/news/nautilus-news.c: (do_destroy), (draw_rss_items),
	(nautilus_news_make_new_channel), (max_items_changed),
	(make_news_view):
	use the preference for max items and update interval

	* libnautilus-extensions/nautilus-global-preferences.c:
	define defaults for news panel preferences

	* libnautilus-extensions/nautilus-global-preferences.h:
	define news panel preferences

	* src/nautilus-preferences-dialog.c:
	add a news panel pane to the preferences dialog