### navigate_to_first_post_after_read setting for categories
When enabled on categories logged on users will return to OP after
reading the entire category. (useful for documentation categories)
### num_auto_bump_daily
Set a number of topics that will automatically bump daily on a category.
- Every 15 minutes we will check if any category has this setting
- Categories with the setting are shuffled
- We exclude pinned, closed, category description and archived topics
- Maximum of 1 topic for the list of categories is bumped till limit reached per category
- We always try to bump oldest first
- Limit is elastic using a RateLimiter that ensures that we only bump N per day
Also some minor organisation on category settings
Froze strings on category.rb
* Phase 0 for user-selectable theme components
- Drops `key` column from the `themes` table
- Drops `theme_key` column from the `user_options` table
- Adds `theme_ids` (array of ints default []) column to the `user_options` table and migrates data from `theme_key` to the new column.
- Removes the `default_theme_key` site setting and adds `default_theme_id` instead.
- Replaces `theme_key` cookie with a new one called `theme_ids`
- no longer need Theme.settings_for_client
When there is a topic draft in place instead of showing "+ New Topic"
we will show "+ Open Draft", this allows topic drafts to be much less
intrusive.
Also, fixes draft handling of tags
This feature can be enabled by choosing a destination for the
`shared drafts category` site setting.
* Staff members can create shared drafts, choosing a destination
category for the topic when it is published.
* Shared Drafts can be viewed in their category, or above the
topic list for the destination category where it will end up.
* When the shared draft is ready, it can be published to the
appropriate category by clicking a button on the topic view.
* When published, Drafts change their timestamps to the current
time, and any edits to the original post are removed.
In the past we used suppress_from_homepage, it had mixed semantics
it would remove from category list if category list was on home and
unconditionally remove from latest.
New setting explicitly only removes from latest list but leaves the
category list alond
