Remove AtomPub from core.

* Will be replaced with http://wordpress.org/extend/plugins/atom-publishing-protocol/.
 * Introduces an action, xmlrpc_rsd_apis, to add APIs to xmlrpc.php?rsd.
 * Introduces support for 'error' being 403 and 50x in class-wp.php.
 * Removes 'Remote Publishing' from Writing Settings (see [21804]). Keeps the remote_publishing settings section.

DB version is bumped to generate the new wp-app rewrite rule and remove the old enable_app option.

props wonderboymusic.
fixes #21509.



git-svn-id: https://develop.svn.wordpress.org/trunk@21818 602fd350-edb4-49c9-b593-d223f7449a82

wp-admin/includes/schema.php

@@ -444,7 +444,6 @@ function populate_options() {
 
 	// 2.6
 	'avatar_default' => 'mystery',
-	'enable_app' => 0,
 
 	// 2.7
 	'large_size_w' => 1024,
@@ -542,7 +541,7 @@ function populate_options() {
 		'_wp_http_referer', 'Update', 'action', 'rich_editing', 'autosave_interval', 'deactivated_plugins',
 		'can_compress_scripts', 'page_uris', 'update_core', 'update_plugins', 'update_themes', 'doing_cron',
 		'random_seed', 'rss_excerpt_length', 'secret', 'use_linksupdate', 'default_comment_status_page',
-		'wporg_popular_tags', 'what_to_show', 'rss_language', 'language', 'enable_xmlrpc',
+		'wporg_popular_tags', 'what_to_show', 'rss_language', 'language', 'enable_xmlrpc', 'enable_app',
 	);
 	foreach ( $unusedoptions as $option )
 		delete_option($option);