Changed

Replaced the scratchpad with a new feature: Documents
Redesigned and reimplemented the search feature.
Replaced delayed_job with Sidekiq, which relies on redis.
Cleaned up code around changing billing plans.
Users must now be logged in to view session-specific pages like recently-edited content and the page template wizards.
Added router-based authentication to the admin pages (using the site_administrator flag).
Upgraded a ton of gems for security and other updates.
Tons and tons of database/query optimizations around the site.
Re-enabled serendipitous prompts for all users.
Changed puma concurrency limit to 1 worker.
Account deletion is now done asynchronously.
Updated copy on the "For Writers" page. Need to do "For Roleplayers" and "For Artists" still.
Replaced all newline characters in existing scratchpad documents with <br />, since documents are now HTML.
Changelogs now also link to pages when using the [[type-id]] link bar format.
The field migration service no longer runs for pages updated after Sept 1, 2018.
Upgraded thredded and customized views.
Replaced therubyracer with mini_racer.

Added

Added 5 page types: Vehicle, Tradition, Building, Condition, and Job.
Added additional fields to existing page types for the new page types (e.g. "Job" on characters).
Added a link to profiles to send private messages to other users. Users no longer need usernames to send messages.
Added a new ContentSerializer PORO for caching attribute categories/fields/values once per page load.
Added skylight for performance monitoring.
Added additional error reporting for users attempting to upgrade to nonexistent billing plans.
Added documents to the undeletion flow. Users can now un-delete documents after deleting them.
Added autosaving functionality to documents.
Added rails_admin.
Added more database indices.
Added a JSON endpoint for pages.

Fixed search.
Fixed exporting to txt/outlines.
Fixed a bug requiring two presses of "tab" to tab between page fields instead of one.
Fixed some static images not loading around the site.
Fixed several behind-the-scenes errors throwing when users navigate to nonexistent content. Users are now redirected back to their dashboard instead of seeing a 500.
Fixed the recently-deleted page linking to deleted pages (which, obviously, would 404).
Fixed several issues around old-style attributes/values in new views.
Fixed a bug around storage space when downgrading from premium.
Fixed a layout bug on some screen sizes on the home landing page.