3.1

• Made PHP redirects faster and more efficient.
• Added an interface to easily serve 410 (content deleted) headers for posts you have just deleted.
• Added support for creating 451 (legal takedown) headers in the redirect manager.
• Improved existing validations, ensuring redirects are complete and unique.
• Added a validation error that checks for a redirect loop.
• Added validation warnings for the following cases:
  • when a redirect points to an url that is redirected.
  • when a redirect point to a url that cannot be resolved.
  • when a redirect points to a url that doesn't return a 200 OK status code.
• Changed the interface for inline editing of redirects to resemble the redirect form used to add redirects.
• Fixes a possible fatal error on update.
• Replaced checkboxes and radio buttons with toggles on the Premium settings pages.
• Makes sure post / term slugs uniqueness checks also take into account redirects.
• Makes sure redirected are redirected both with and without trailing slash.
• Takes the WP permalink structure into account in deciding if we should redirect to a slug with or without trailing slash.
• Makes sure links to our knowledge base open in a new window.
• Added a few knowledge base suggestions to our support beacon on the redirects page.
• Merge with Yoast SEO 3.1.