• A new Languages component for debugging languages and text domains. Thanks, @MPolleke!
• REST API debugging in the form of HTTP headers when performing an authenticated REST API request. Shows PHP errors when relevant, along with an overview of memory usage, processing time, database query number, and database query time.
• Various visual improvements, including displaying the relevant file name below stack trace functions, and a more visible stack trace expansion toggle.
• Add is_embed(), is_comment_feed(), and is_user_admin() to the list of conditional functions.
• Add HHVM, SAPI, and MySQL client info to the Environment component.
• QM is now not loaded at all on the CLI.
• Avoid an issue with the CloudFlare Flexible SSL plugin.
• Improve the output of Multisite's $current_blog and $current_site in the Request component.
• Fully handle Windows paths when detecting a file component.
• Don't display the symlink warning when using a secondary instance of WPDB.
• Whole bunch of internal structure refactoring, escaping, and other misc tweaks.