Remove ancient 'lookup' quicktag from the text editor. This had called up answers.com.

props mboynes, jonbishop, SergeyBiryukov.
fixes #23322.



git-svn-id: https://core.svn.wordpress.org/trunk@24052 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Add wp_registration_url() and register_url filter.

props scribu, JustinSainton, SergeyBiryukov.
fixes #17950.



git-svn-id: https://core.svn.wordpress.org/trunk@24053 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Document that fetch_feed() can accept multiple URLs, thus leveraging SimplePie's multifeed feature. props JustinSainton, fixes #22140.



git-svn-id: https://core.svn.wordpress.org/trunk@24054 1a063a9b-81f0-0310-95a4-ce76da25c4cd