* gnus-cache.el (gnus-summary-insert-cached-articles): Use

	* gnus-cache.el (gnus-summary-insert-cached-articles): Use
	gnus-summary-limit.

	* gnus-range.el (gnus-add-to-sorted-list): New function.
	* gnus-sum.el (gnus-mark-article-as-read): Use it.
	(gnus-mark-article-as-unread): Ditto.
	(gnus-summary-mark-article-as-unread): Ditto.
	(gnus-build-get-header): Ditto.
	(gnus-summary-prepare-threads): Ditto.
	(gnus-summary-insert-pseudos): Ditto.
	(gnus-articles-to-read): Use gnus-sorted-union and gnus-sorted-nunion.
	(gnus-summary-insert-new-articles): Use gnus-sorted-nunion.
	(gnus-summary-insert-old-articles): Ditto.