+* $wgJpegPixelFormat was added to override chroma subsampling for JPEG image
+ thumbnails created via ImageMagick. Defaults to 'yuv420', providing bandwidth
+ savings versus the previous behavior on many files.
+* MediaWiki\Auth infrastructure (called "AuthManager") allows for more flexible
+ configuration of multiple authentication pieces that was possible with
+ AuthPlugin. For example, it's now easy to plug in second-factor
+ authentication, or add additional checks to the login process, or to support
+ multiple login methods at once, or to support non-password-based login methods.
+** Providers are configured via the global setting $wgAuthManagerConfig.
+** A global, $wgDisableAuthManager, is temporarily available to disable
+ AuthManager until extensions are ready to support it.
+** New hook, AuthChangeFormFields, to adjust the form fields on
+ AuthManager-related special pages.
+** New hook, AuthManagerLoginAuthenticateAudit, for additional logging of
+ AuthManager-related authentication requests.
+** New hook, ChangeAuthenticationDataAudit, for additional logging of
+ AuthManager-related authentication data changes.
+** New hook, SecuritySensitiveOperationStatus, to work with the new mechanism
+ for requiring a recent login before taking security-sensitive operations
+ like changing a password.
+** Two new globals, $wgChangeCredentialsBlacklist and $wgRemoveCredentialsBlacklist
+ can be used to prevent the web UI and the API changing certain authentication data.
+* The file upload dialog (available if you install WikiEditor or VisualEditor)
+ can now be configured using $wgUploadDialog.