Carousel: Switch slide when pressing back/forward buttons

Before this change, the browser's back and forward
buttons would update the URL with the ID of the
desired slide, but the UI would not actually
update.

The problem was that the `open` method was getting
called for `onhashchange` events, but it would do
nothing if the carousel was already activated.
This patch adds a new method that will switch the
slide even if the carousel is already open.
Debugger: Standardized all fonts to reload the page instead of some opening a new window
Update grunion-contact-form.php

$content need to be a string.
Whitespace and Brackets.
Be more careful with extracts.
Do a bit more regex checking against the URL.
Add WordPress SEO Premium by Yoast

as per
https://wordpress.org/support/topic/disable-opengraph-in-jetpack?replies
=10#post-5538081
Merge pull request #514 from richardmtl/yoast-seo-premium

Add WordPress SEO Premium by Yoast
Merge pull request #415 from rads/rad/back-button

Carousel: Tie browser forward/back buttons to carousel controls when navigating through carousel's history
Tiled Gallery: Remove 5 px width adjustment.

The grouper used in computing the layout for rectangular galleries initially had a 5 pixel adjustment in it's content width: `$content_width - 5`, which was documented to be there for broken themes and rounding errors. After some discussion in #443, @ethitter concluded that it should be safe to remove the adjustment.
Merge pull request #513 from turtlepod/patch-1

Resolve string/array confusion around comment forms.
Tiled Galleries: Don't require Photon in dev mode.

So that Tiled Galleries work reasonably well in dev mode, let's not require a connection for Tiled Galleries, and just not try to pass the images through Photon if we are in dev mode.
Carousel: advance carousel when activating browser's forward/back buttons

Since Carousel pushes URL fragments into the browser history, advancing back and forth through the browser history for Carousel using the browser buttons should trigger Carousel to change slides.

Fixes #6307. Props rads.

Merges r97029-wpcom.
Jetpack CPTs: make sure the portfolio, testimonial, and comic post types are registered during imports.

The post types are normally loaded if the active site's theme supports those features. During async imports,
some default theme is used which doesn't have support for these features, which means that these types of
posts are skipped during imports.

As these post types could be used on any dotcom site, and are also distributed with the Jetpack plugin,
making sure that these post types are registered during imports will provide a consistent import experience.

See https://[private link]

Merges r97058-wpcom.
Jetpack CPTs: make sure the portfolio, testimonial, and comic post types are registered during imports.

The post types are normally loaded if the active site's theme supports those features. During async imports,
some default theme is used which doesn't have support for these features, which means that these types of
posts are skipped during imports.

As these post types could be used on any dotcom site, and are also distributed with the Jetpack plugin,
making sure that these post types are registered during imports will provide a consistent import experience.

See https://[private link]

Merges r97058-wpcom.
Merge commit 'cf21349'
Grunion: bail out of `grunion_manage_post_columns()` early if we're not rendering a custom column type that belongs to Grunion.

Prior to this change, `Grunion_Contact_Form_Plugin::parse_fields_from_content()` was being called for each post inside any WP_List_Table.
As this method invokes the `the_content` filter, it was causing WordPress to unnecessarily render each post, including fetching oEmbeds.

In some edge cases, this hurt performance for posts that have a lot of oEmbed'd content, preventing the user from loading wp-admin/edit.php.

See https://[private link]

Merges r97112-wpcom.
REST API : Suggest : Mentions : Add optional avatar_size parameter and wire through remainder of API - see http://[private link]

Merges r97224-wpcom.
API : Add array cast to protect against bad endpoint definitions - see http://[private link]

Merges r97199-wpcom.
REST API: fix some inconsistencies in media handling

* centralize a single function for handling media sideloading, which gracefully fails if called in a non-upload context
* add missing request params for the Edit Post endpoint
* create/edit post endpoint: code for handling media was wrapped in `$is_new` so it wasn't working for edits

Merges r97200-wpcom.