Fix threadmark index ordering (restore ascending ordering)
Threadmark Rss feed is now sorted by most recent to oldest and now has a configurable fetch limit (default 10)
Restore creating the threadmarks_read table for new installs
When the "No index reader mode pages" option is set, only apply noindex meta tag to reader mode views, not all threads.
Add no-index option for reader mode (default enabled)
Tweak indexes on threadmark tables
Respect thread locked state when adding/editing/deleting threadmarks
Surface some threadmark info as data attributes on threadmark index
Include Like count when fetching threadmarks, useful for theming on a thread's index page.
Elasticsearch v6 single-type support is complex so move it into https://xenforo.com/community/resources/enhanced-search-improvements.4762/
Cache phrase names for threadmark categories, and avoid ~2 queries with threads with threadmarks
Option to disable threadmark stats block
Support other add-ons injecting content into each thread per-category cache.