Pass $post object to 'preview_post_link' filter.

props danielbachhuber.
fixes #28729.

git-svn-id: https://develop.svn.wordpress.org/trunk@28969 602fd350-edb4-49c9-b593-d223f7449a82
Prevent sending a 404 status when returning the response for the customize preview, since it causes the jQuery Ajax to fail. Send 200 instead.

props westonruter.
fixes #27992.

git-svn-id: https://develop.svn.wordpress.org/trunk@28970 602fd350-edb4-49c9-b593-d223f7449a82
Fix texturization of quotes when enclosed by angle brackets.

props miqrogroove.
fixes #28718.

git-svn-id: https://develop.svn.wordpress.org/trunk@28971 602fd350-edb4-49c9-b593-d223f7449a82
Improve oEmbed caching. Introduces the concept of a TTL for oEmbed caches and a filter for `oembed_ttl`.

We will no longer replace previously valid oEmbed responses with an `{{unknown}}` cache value. When this happens due to reaching a rate limit or a service going down, it is data loss, and is not acceptable. This means that oEmbed caches for a post are no longer deleted indiscriminately every time that post is saved.

oEmbed continues to be cached in post meta, with the addition of a separate meta key containing the timestamp of the last retrieval, which is used to avoid re-requesting a recently cached oEmbed response. By default, we consider a valued cached in the past day to be fresh. This can greatly reduce the number of outbound requests, especially in cases where a post containing multiple embeds is saved frequently.

The TTL used to determine whether or not to request a response can be filtered using `oembed_ttl`, thus allowing for the possibility of respecting the optional oEmbed response parameter `cache_age` or altering the period of time a cached value is considered to be fresh.

Now that oEmbeds are previewed in the visual editor as well as the media modal, oEmbed caches are often populated before a post is saved or published. By pre-populating and avoiding having to re-request that response, we also greatly reduce the chances of a stampede happening when a published post is visible before oEmbed caching is complete.

As it previously stood, a stampede was extremely likely to happen, as the AJAX caching was only triggered when `$_GET['message']` was 1. The published message is 6. We now trigger the caching every time `$_GET['message']` is present on the edit screen, as we are able to avoid triggering so many HTTP requests overall.

props markjaquith. fixes #14759. see #17210.


git-svn-id: https://develop.svn.wordpress.org/trunk@28972 602fd350-edb4-49c9-b593-d223f7449a82
Correct typo in `sanitize_html_class()` docblock.

git-svn-id: https://develop.svn.wordpress.org/trunk@28973 602fd350-edb4-49c9-b593-d223f7449a82
Use the admin scheme for theme preview URLs when installing new themes. See #21919.

git-svn-id: https://develop.svn.wordpress.org/trunk@28974 602fd350-edb4-49c9-b593-d223f7449a82
Fix an incomplete docblock for `wp_create_categories()` as part of `$post/$post_id` cleanup.

See #28388.


git-svn-id: https://develop.svn.wordpress.org/trunk@28975 602fd350-edb4-49c9-b593-d223f7449a82
Remove backticks on `$post` variables in some short parameter descriptions.

See [28653], [28654].
See #28388.


git-svn-id: https://develop.svn.wordpress.org/trunk@28976 602fd350-edb4-49c9-b593-d223f7449a82
Clarify the inline documentation for `plugins_url()` to reflect that it also works with mu-plugins.

Props ericlewis.
See #28499.


git-svn-id: https://develop.svn.wordpress.org/trunk@28977 602fd350-edb4-49c9-b593-d223f7449a82
Simplify the setup-config.php UI flow and load process.

When no configuration file is detected, we now redirect to setup-config.php. This process now uses the WordPress bootstrap, rather than a set of fragile hacks.

fixes #28740.


git-svn-id: https://develop.svn.wordpress.org/trunk@28978 602fd350-edb4-49c9-b593-d223f7449a82
Note in the hook docs for `preview_post_link` that the `$post` parameter was added.

See #28729.


git-svn-id: https://develop.svn.wordpress.org/trunk@28979 602fd350-edb4-49c9-b593-d223f7449a82
Don't escape customizer control descriptions, just as section descriptions are not escaped. These are set programmatically, not via user input. props tollmanz. fixes #27981.


git-svn-id: https://develop.svn.wordpress.org/trunk@28980 602fd350-edb4-49c9-b593-d223f7449a82
Remove a toolbar CSS hack for a Chrome bug that no longer appears to exist. props avryl. fixes #28606. see #18868.


git-svn-id: https://develop.svn.wordpress.org/trunk@28981 602fd350-edb4-49c9-b593-d223f7449a82
Merge branch 'master' of git://develop.git.wordpress.org